Public Cloud vs. Private Cloud - What are the key dif­fer­ences?

Public and private clouds differ in terms of access: a public cloud is shared by multiple busi­ness­es or private users, while a private cloud is dedicated to just one entity. Since the range of services can vary sig­nif­i­cant­ly between different clouds, it’s important to un­der­stand the dif­fer­ences, as well as the ad­van­tages and drawbacks of each option.

The dif­fer­ences between public cloud vs. private cloud

When choosing between various cloud models, there isn’t a one-size-fits-all approach. Each cloud model offers unique ad­van­tages and drawbacks, depending on specific needs. The public cloud is one of the most popular services, requiring only a browser from its users. On the other hand, the private cloud is ideal for busi­ness­es that prefer in­de­pen­dent IT in­fra­struc­tures and their own data centers. Many private users also opt for it to store photos and other crucial data.

To make the right choice, you should know the dif­fer­ences between a public cloud and a private cloud. Since the services of the two are now merging seam­less­ly, dif­fer­ences and sim­i­lar­i­ties may even overlap at times.

Multi-tenancy

In the public cloud, multiple tenants share the IT in­fra­struc­ture, meaning that private users or busi­ness­es use resources together. This leads to high-cost ef­fi­cien­cy because the in­fra­struc­ture is utilized by multiple parties. However, this approach can pose a security risk under certain cir­cum­stances, par­tic­u­lar­ly with strict reg­u­la­to­ry com­pli­ance re­quire­ments, as sensitive data may not be com­plete­ly isolated.

In contrast, the private cloud offers a dedicated in­fra­struc­ture that is used ex­clu­sive­ly by a single company or tenant, reducing the risk of data mixing or unau­tho­rized access. Thus, the private cloud is better suited for busi­ness­es with strict data pro­tec­tion re­quire­ments.

Location of the in­fra­struc­ture

The public cloud is typically hosted off-premises in non-local data centers operated by cloud providers, which are usually located outside the company’s physical in­fra­struc­ture. This allows for high scal­a­bil­i­ty and out­sources main­te­nance and man­age­ment to the cloud provider.

It’s different with private clouds, which can operate both in the company’s own data centers and in ex­clu­sive­ly hosted cloud en­vi­ron­ments. This flex­i­bil­i­ty allows busi­ness­es to either manage the in­fra­struc­ture entirely in-house or use dedicated resources from a cloud provider, while main­tain­ing control over the en­vi­ron­ment within the company.

Pro­vi­sion­ing of services and ap­pli­ca­tions

In the public cloud, services and ap­pli­ca­tions are hosted on the cloud provider’s IT in­fra­struc­ture. This setup allows both ap­pli­ca­tions and data to run on the provider’s resources, sim­pli­fy­ing de­ploy­ment but also creating a level of de­pen­dence on the provider’s in­fra­struc­ture.

In contrast, with the private cloud, services and ap­pli­ca­tions are kept within the company’s own network. This setup offers more control and security, as there are no shared resources with other companies or private users, ensuring better isolation and stronger security guar­an­tees.

Offer models

While public cloud services are typically offered in various pre­de­fined sub­scrip­tions, plans, or complete packages, a private cloud can be tailored precisely to the specific needs of a company. This means that busi­ness­es can develop cus­tomized solutions for their in­di­vid­ual needs, which requires more effort in im­ple­men­ta­tion but also provides greater flex­i­bil­i­ty and control over cloud services.

Security

Despite state-of-the-art security measures and highly secured data centers, the multi-tenant approach of the public cloud can pose a security risk in some cases, es­pe­cial­ly with very strict reg­u­la­to­ry com­pli­ance re­quire­ments. Since multiple companies share the same in­fra­struc­ture, security gaps could po­ten­tial­ly affect other tenants.

In contrast, the private cloud offers higher security pre­cau­tions since the IT in­fra­struc­ture is provided ex­clu­sive­ly for one company, allowing for a higher level of control and isolation. This makes the private cloud par­tic­u­lar­ly suitable for companies with high demands on data pro­tec­tion and security standards, such as in reg­u­la­to­ry or business-critical areas.

In­vest­ment in in­fra­struc­ture

Public cloud services don’t require major in­vest­ments in in­fra­struc­ture, as the IT en­vi­ron­ment is managed and provided by the cloud provider. Companies usually pay based on their actual resource usage.

The private cloud, in contrast—es­pe­cial­ly when operated on-premises or in exclusive cloud en­vi­ron­ments—often requires high in­vest­ments in hardware and software.

An overview of the dif­fer­ences between the private cloud and public cloud

Ad­van­tages and dis­ad­van­tages of both cloud models

The ad­van­tages and dis­ad­van­tages of a public or private cloud model are defined not so much by its weak­ness­es, but by in­di­vid­ual tenant re­quire­ments. For example, public clouds offer highly scalable IT resources, with an in­fra­struc­ture shared among other users. For users like gov­ern­ment agencies, security services, or financial in­sti­tu­tions, the multi-tenancy and an external cloud IT may be con­sid­ered a small but un­ac­cept­able security risk. Private clouds, on the other hand, offer high security standards but require in­vest­ments in building an on-premises cloud en­vi­ron­ment.

Ad­van­tages and dis­ad­van­tages of the public cloud

Using public cloud services offers companies numerous ad­van­tages, es­pe­cial­ly by out­sourc­ing IT operating costs to cloud providers. This results in cost savings, as companies only pay for the resources actually used, while also having easy access to a cost-effective and always-updated cloud en­vi­ron­ment. Managed public cloud services also ease the server man­age­ment and com­pli­ance with security and com­pli­ance standards, which par­tic­u­lar­ly benefits smaller companies with limited IT resources. Ad­di­tion­al­ly, these cloud services can be scaled and updated as needed, providing companies with flex­i­bil­i­ty and agility.

However, there are also risks as­so­ci­at­ed with using the public cloud. The multi-tenancy of the public cloud can present an un­ac­cept­able security risk for companies with high reg­u­la­to­ry com­pli­ance and security re­quire­ments. Ad­di­tion­al­ly, using external cloud services can lead to a de­pen­den­cy on the provider’s IT en­vi­ron­ment, which limits control over the in­fra­struc­ture.

Another issue is that the cloud in­fra­struc­ture is not always located in the client’s country, which can lead to security gaps and concerns about data sov­er­eign­ty due to differing leg­is­la­tions, such as the US Cloud Act. Lastly, many public cloud providers often do not offer tailored solutions for busi­ness­es, but instead provide pre-con­fig­ured sub­scrip­tions or packages that may not always meet a company’s specific needs.

Ad­van­tages and dis­ad­van­tages of the private cloud

A private cloud also offers a range of specific ad­van­tages. It is char­ac­ter­ized by highest security standards, as the in­fra­struc­ture is exclusive and company-owned. This ensures high control over data and the IT en­vi­ron­ment. Companies can operate the private cloud both on-premises with their own IT resources and off-premises with vir­tu­al­ized resources main­tained by Managed Cloud Hosting. Another advantage is the flexible and quick access to the internal IT en­vi­ron­ment for selected user groups. Ad­di­tion­al­ly, cloud services in the private cloud can be tailored to the specific needs of the company and expanded.

However, there are also some dis­ad­van­tages. The private cloud requires a higher (initial) in­vest­ment for exclusive cloud services as well as IT resources, hardware, and software licenses. Ad­di­tion­al­ly, flex­i­bil­i­ty is somewhat more limited compared to the public cloud. With an on-premises private cloud without vir­tu­al­iza­tion, building and main­tain­ing IT ca­pac­i­ties can require ad­di­tion­al effort. There is also the risk that on-premises cloud servers with in­ad­e­quate IT security are more sus­cep­ti­ble than the highly secure servers of cloud providers.

Use cases of public clouds and private clouds

Public cloud

Where the public cloud is used doesn’t depend so much on the industry or the company, but on the company’s own resources and IT needs. The public cloud is par­tic­u­lar­ly suitable for high scal­a­bil­i­ty and pro­cess­ing large workloads. Companies that both offer and use public cloud tech­nol­o­gy are:

• AWS (Amazon Web Services)
• Microsoft Azure Ex­press­Route
• IBM Blue Cloud
• Google Cloud Platform
• Alibaba Cloud
• Oracle Cloud Fast­Con­nect

Es­pe­cial­ly for companies with limited IT resources that want to focus on their core business while handling enormous amounts of data, the highly scalable public cloud ca­pac­i­ties are suitable. Well-known companies using public clouds or hybrid clouds include:

• Netflix: The streaming service has been using the AWS cloud since 2016 and therefore no longer maintains its own data centers. This step has resulted in sig­nif­i­cant cost savings as well as an increase in the number of streaming users.
• X (formerly Twitter): The social media platform is in a part­ner­ship with Google and transfers large amounts of data to the Google Cloud. In addition to the scal­a­bil­i­ty gained, it was the various at­trac­tive cloud features that motivated X to make this decision.
• Lufthansa: The airline decided in 2020 to leverage Google Cloud to improve its work processes. For instance, the planning of aircraft de­ploy­ment and main­te­nance is handled via the cloud.

Private cloud

Companies and private users who value maximum autonomy and in­de­pen­dence rely on a private cloud en­vi­ron­ment, which can be im­ple­ment­ed both with a local IT en­vi­ron­ment and via vir­tu­al­iza­tion off-premises. Companies that offer private and hybrid cloud services are:

• Oracle
• IBM
• VMware
• Hewlett Packard En­ter­prise
• Amazon Virtual Private Cloud
• Google Virtual Private Cloud
• Ubuntu OpenStack (Open Source)
• Apache Cloud­Stack (Open Source)

Well-known companies or or­ga­ni­za­tions that rely on their own private cloud or hybrid cloud include:

• Walmart: The retail giant has invested several million dollars in its cloud system. Improved data handling aims to boost sales and enhance com­pet­i­tive­ness in the re­lent­less e-commerce com­pe­ti­tion.
• NASA: The American aerospace agency has a cloud data center called “Nebula,” which combines private cloud and open source. NASA employees can, for example, share their research data much more easily with business partners and others.
• U.S. De­part­ment of Defense: The U.S. De­part­ment of Defense uses a hybrid cloud system for secure data man­age­ment and op­er­a­tions, enabling efficient col­lab­o­ra­tion across various branches while main­tain­ing the necessary security protocols.

What other cloud models are there?

In addition to the private cloud and public cloud, users have a choice between two other cloud models that result from a com­bi­na­tion of the two pre­vi­ous­ly presented models:

1. Hybrid Cloud: Combines cloud services from public and private clouds using local data centers and external public cloud services. With the hybrid model, companies can dis­trib­ute services and ap­pli­ca­tions between private and public clouds. Since public clouds offer es­pe­cial­ly powerful ca­pac­i­ties, the high security of a private cloud can be connected with the per­for­mance of public clouds. Costs can also be adjusted to meet re­quire­ments through the flexible dis­tri­b­u­tion of workloads.

2. Multi Cloud: Rep­re­sents the si­mul­ta­ne­ous use of the same cloud model (either public or private cloud) from different cloud providers. Companies thus use multiple private or public clouds in parallel.

Closely linked to the form of cloud de­ploy­ment is also the type of services and functions offered within the framework of cloud computing. Here are three main types to dis­tin­guish:

1. IaaS: Provides instantly available IT resources and scalable network in­fra­struc­tures virtually over the internet.
2. PaaS (Platform-as-a-Service): Provides APIs via the cloud or the internet as a developer and computing platform for ap­pli­ca­tion de­vel­op­ers.
3. SaaS (Software-as-a-Service): Software and IT en­vi­ron­ments are provided by third-party vendors as a service, either as complete packages or demand-based models.