SmartMusic lets you have cues, build in specific spots where it "listens" to and "follows" the player, and is more adaptable. It's not native to SM all the time - there is a built-in limited amount of following, but not 100% - but for example if you are playing a piece that has a cadenza or a tempo change, you want to make sure you have enough time to PLAY that cadenza without having to through and tap the SM again. Or to do the tempo change without having to do it exactly the same way every time.

It's more than just dumping a finale file into it.