Name one.
Well, we have gone into that already. The thematic urgency and immediacy (often without the ornamention or fancy bridges you hear in concert music), the abrubt changes within cues to fit onscreen split timings, and the more developed (or extreme) uses of elements that already existed in concert music (some of those horror film gimmicks, for example). Again, I’m not denying that the seeds of some of these things already existed in other types of music, but film music has taken it and turned it into its own thing. More pointed, specified. More “unstable”. More whimsical, if you will.
I think that’s about as far as I can describe it, as a person with no musical education. Most of the time, I recognize film music when I hear it. In some rare cases, I’m more in doubt.