From what I've understood after reading many, many, threads on this site, and talking to people on the course. As well, discussing with my friends:
SNAP: A qualitate term to describe the number of rpms exerted upon the disc, around an axis perpendicular to the flight plate, resulting from the sudden rotation of ones hand about the wrist at the end of a throw.
HIT: A sequence of bio-mechanical actions involving the entire body, used to describe when and how a disc should be positioned through the latter half of a backhand golf throw (not including follow-through).
But I could be wrong