They are essentially the same. They both are capable of doing gigabit if you make them properly, like less than 1/2" of untwisted wire in the plugs, etc. Cat5e was kinda an semi-unofficial extension to the normal cat 5 to get a little better chance of doing gigabit. Cat6 was the official standard, I think cat6 supports multi gigabit.
Anyway the wire standard is all the same. Then are pin and plug compatible and if you are doing gigabit or less ethernet, they are compatible with that.
Me, I bought a 1000' spool of cat5e for $45 complete with connectivity tester, crimper, 100 plug ends. Later I bought a 1000' spool of cat 6 with crimper and plug ends for around $55. I like to work with cat5e more, cat6 has this plastic insert in the cable that is a freaking PAIN to make your own cables with. Unless there's a trick to it I dont know. But if you are buying premade that mini rant doesn't matter
