SaaS vs. PaaS vs. IaaS: A Clear Comparison Table | IT Passport Exam Prep
A clear breakdown of the three cloud service models—SaaS, PaaS, and IaaS—using a comparison table covering responsibility scope, representative services, and key exam points.
The Three Cloud Service Models
IaaS, PaaS, and SaaS are distinguished by the boundary of responsibility—specifically, how much management the cloud provider handles. All three share the common trait of being used over the internet without owning physical servers on-site, but they differ in which layers (network, OS, middleware, applications) are managed by the user versus the provider.
Responsibility Scope Comparison Table
| Category | Application | Data | Middleware | OS | Server, Storage, Network |
|---|---|---|---|---|---|
| On-Premises | User | User | User | User | User |
| IaaS | User | User | User | User | Provider |
| PaaS | User | User | Provider | Provider | Provider |
| SaaS | Provider | User | Provider | Provider | Provider |
This table is the most important thing to remember. The exam repeatedly asks questions like "Who is responsible for managing the OS?" or "Who provides the application?" to test your understanding of responsibility boundaries.
Representative Services and Use Cases
Typical IaaS examples include AWS EC2, Azure Virtual Machines, and Google Compute Engine—a model for developers who want full control over server configuration. PaaS is represented by Heroku, Google App Engine, and AWS Elastic Beanstalk, ideal for teams that want to focus on application development while leaving OS and middleware management to the provider. SaaS includes Microsoft 365, Salesforce, Slack, and Gmail—software that end users can start using immediately.
Key Exam Points for the IT Passport
For a question like "Which cloud service allows users to develop the application?", the correct answer is either IaaS or PaaS. Checking the "Application = User" row in the comparison table gives you the answer instantly. Hybrid cloud (combining on-premises with cloud) and multi-cloud (using multiple cloud providers) also appear on the exam. Additionally, when comparing on-premises and cloud, be sure to understand the difference between initial costs (CapEx) and operational costs (OpEx), as well as scalability levels.
Related Terms
Virtualization technologies (hypervisors, containers) that form the foundation of IaaS are also important concepts tested in the Technology domain. APIs and microservices may appear on the exam as architectures that pair well with PaaS. The cloud is also positioned as a key driver of DX (digital transformation), detailed in What is DX, and is often tested together with Strategy-related topics.
Study Tips
If you can reproduce the comparison table from memory on a blank sheet of paper, you'll be able to handle exam questions quickly. Being able to name three representative services for each model will help you avoid confusion when faced with tricky answer choices. The ability to instantly answer who manages the "application, OS, and hardware" layers is the benchmark for passing.
Summary
The difference between the three models comes down to the boundary of responsibility. Once you memorize the table and know the representative services, cloud-related questions become a reliable source of points. You can practice 906 questions on frequently tested Strategy topics in the Strategy Category Summary. Be sure to review other areas together with a practice exam in a simulated test format.
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