What are the differences on pda phones & smart phones? does all pda/smart phones comes with CPU?

Hi there, PDAs are mostly block shapped phones that needs a stylus(Stick) to touch the screen for interface. Most PDAs are being challenged by Smartphones which are like e.g Nokia E or N-Series which is like a mini computer. In Nokia's smartphones like above, softwares can be installed for other usages like PC. So think about it. And by the way, All phones these days comes with a CPU!