What is difference in

say p3 600 and p3 600e
what do the e stand for and are there other letters after processors? if so what do they mean?

The "e' letter at the end means it runs at a default 100 MHz FSB. If it says "eb" at the end, it was designed to run at 133 MHz. Often, the "e" is dropped off the end, especially if there is no "eb" version of that chip.

If I'm not mistaken the E means that it is a coppemine chip. These have a smaller micron trace that allows the chip to run cooler and acheive better speeds....