Three commonly used terms

IaaS - Infrastructure as a Service

PaaS - Platform as a Service

SaaS - Software as a Service

Additional terms

CaaS - Container as a Service

FaaS - Function as a Service

The differences between these concepts lies in their levels of abstraction

Infrastructure as a Service

Open

The cloud provider provides and manages the tins and wire upon which you build your environment. When we say provide, we mean to maintain the existence of the tech versions at this stack and the tools to install and upgrade the tech at this level of the stack. You must provide the Operating System, Runtime libraries for the applications you want to host, database servers, and the applications

Platform as a Service

Open

The cloud provider additionally provides and manages the Operating and Runtime libraries. When we say provide, we mean to maintain the existence of the tech versions at this stack and the tools to install and upgrade the tech at this level of the stack. You must provide the database servers and the applications. Examples of this would be a machine providing the environment for mobile phone development.

Software as a Service

The cloud provider additionally the required application. When we say provide, we mean to maintain the existence of the tech versions at this stack and the tools to install and upgrade the tech at this level of the stack. Examples of this would be email services such as Hotmail, google mail, yahoo, etc, Office 356, Google Docs, Atlassian Confluence, and Jira

AWS

Amazon Web Services offer all of these services