What makes it a PaaS not SaaS - or examples

Question

I found some questions here on how to create a SaaS. This much is easy, but what I don't understand is what makes an application a PaaS and not a SaaS. What lines does an application cross before we can start calling it a PaaS (platform as a service) and not just a SaaS (software as a service)? It seems like a small difference but I can't pinpoint it.

I would welcome even examples of PaaS if you can point something about them that makes them a PaaS and not a SaaS. A common name in this area is salesforce but I don't know much about the service itself to understand from it why it's a PaaS.

Edit: I feel that from a programmer's perspective, it's the same job, or no? I think the only difference is the PaaS is for developers as end users and SaaS is for regular users as end users. Does that sum it up?

Answer 1

Using Salesforce.com as an example - they offer the Force.com platform, which provides a database, a programming language, integration features and so on. You can use this platform to build whatever you need/like.

Salesforce also offer their own, prebuilt CRM applications - this is software-as-a-service as the application has been built for you, you simply start using it.

PaaS provides you with the components and tools to build something; SaaS provides you a prebuilt application you can pick up and use straight away. The line can be blurred - again, using the Salesforce example, you can tailor their SaaS offerings by using some of their PaaS technologies.

Answer 2

On the surface it looks pretty simple; Think of Amazon's EC2 or Microsoft's Azure as PaaS and various Services (like a weather serivce) or CMS as SaaS.

PS. Try searching for "PaaS vs. SaaS" on google.

Answer 3

This definition is also pretty common:

• Level 1: IaaS > Virtualization, Server, Storage, Network (AWS, Rackspace …)
• Level 2: PaaS > Runtime, Middleware, OS (Heroku, appfog, dotcloud …)
• Level 3: SaaS > Application, Data (most startups)