The great faux pas of young musical theatre enthusiasts is that they will use the words "soundtrack" and "cast recording" interchangeably, or omit the latter and defer to the former as a catch-all. Let's clear things up, once and for all: if it's a recording of a movie musical, it's a motion picture soundtrack. If the recording is of a Broadway show, it's an original cast album or cast recording. Never the twain shall meet.