Nothing but A
##Nothing but A MeansMeans only A. You don't want anything else.
Anything but A
##Anything but A MeansMeans that you don't want A. You could have B or C, or maybe even both B and C (and even E if someone offers) - but NOT A!
Everything but A
##Everything but A MeansMeans that A is the only thing you don't want. You do want the rest of the entire alphabet - but NOT A!