hi i m swapnil
An application server has applications installed on it 
which users on the network can then run as if they were 
installed on the workstation they are using.

A database server has programs installed that allow it to 
provide database services over a network. The data, 
queries, report generatores, etc are all stored on the 
server, while the client machines use a front end to access 
those services.
regards
swapnil