In this opportunity we are going to talk about some of this component:
Web Sites: Web sites in windows azure allow you to create a web site using visual studio the same way that you use to do it on an on-premise scenario and publish it on the cloud. When you create a web site you can use either create a ASP.NET web form or ASP.NET MVC, this way you can just take care of your application and not about the servers administration, on other hand you count with the possibility of use several instance running your application having fault tolerance and a better performance.
Cloud services: the cloud services are composed for two types of roles, Worker Roles and Web Roles, this approach offer a solution with most possibilities for escalation and a better utilization of the resources because you can create as many instances as you can for any type of role so you can create different numbers of instance for Web Roles (run on IIS) and Worker Roles.
The Web Roles is the role running on IIS and serve the user request, while the Worker roles we can compared with Windows Services that are running and listening for petitions or executing a recurrent process. This way a web role instance might accept requests from users and then pass them to a worker role instance for processing.