as part of my project I need to develop a eclipse plugin and am confused between this two concept PDE and RCP .Now I used the PDE solution and it works good but am wondring what is the benifit of using RCP for developing a plugin and should I switch to it?
You are confusing terms here.
PDE is the ‘Plugin Development Environment’ that you use to develop Eclipse plugins. You use PDE to develop plugins regardless of their intended use.
RCP is a ‘Rich Client Program’. This is a collection of plugins that together form a complete application. Eclipse itself is a RCP (a rather complex one).