I have a Generic App in which by making few changes i can make different app for different clients. I have a confusion that do i have to make different App ID everytime i will make a new app in the developer profile.
Each distinct app needs its own App ID.
However, for development/debugging, you can create a wildcard app ID consisting of the string * which will let you use a single development provisioning profile for all your apps.
Only when it comes to distribution (via the app store or adhoc/enterprise) will you need to create the app IDs and profiles.