I just recently rooted my Moto Droid on friday night and am thoroughly enjoying playing with ROM Manager and Metamorph, etc. I was curious as I keep seeing the 'ol, "Make a Nandroid backup". I understand it's a backup, but so are Clockworkmod and SPRecovery... So my question is what exactly is the difference between Clockwork vs. SPRecovery vs. Nandroid? Forgive me if this has been asked before and I failed to find it.