input recall is when you turn the television back on, and it remembers what input you used last. for instance.. if I was using the video 1 input, if I turn my tv back on and it starts up on cable 3, then it doesn't have input recall.
if power to a television is cut while it's on, then it is restored (unplugged, power strip turned off, etc) and the tv starts itself back up, that is power return.
does that make sense?
the reason people want these in a MAME television is so that they can power up the whole setup with one button.