1.IaaS gives you infrastructure, PaaS gives you a development platform, and SaaS gives you ready-to-use software.
2.IaaS (Infrastructure as a Service) gives you the most control over virtual machines and operating systems.
Example: AWS EC2
3. SaaS – Software as a Service.
4.The Cloud Service Provider .
5.IAAS - Eg: AWS EC2
PAAS - eg: Google app engine
SAAS - eg: Google docs