Well, BQP and FBQP are very different concepts, but I doubt anyone who hasn't actively studied complexity theory in the last few years could explain the differe

Well, BQP and FBQP are very different concepts, but I doubt anyone who hasn't actively studied complexity theory in the last few years could explain the difference. Same goes for NP-complete and Entscheidungsproblem; if you don't use it, you lose it. I mean, anybody with a CS degree should know that the halting problem has something to do with predicting whether a given Turing machine will ever stop; but that's not "explain it to your grandmother" level.