How are older computing models different from cloud computing?

Normally web providers or whoever, would use large servers to do all their tasks, be it storing info or number crunching.


an exampel would be Folding@Home.


This could be ran on a super computer, but it would cost alot of money to do. so they made the software andhome users run it at no cost to F@H, the many seprate PC's have the accumaltive proceesing power of a super computer (actually the entire prossecing power supersedes the IBM Roadrunner)


Not all services benifit form Cloud computing, but it is a very intresting branch of computing that could help out alot in hte future, such as Seti and F@H which jsut would be too costly to run on a Supercomputer.