I really don't see F# as being a lot like OCaml in any practical way.

It's like, if you're sitting in a hardware store having a hard time choosing between buying a Ryobi brand miter saw and a Ryobi brand power drill for your current project, maybe it's time to take a step back to better define what you're planning to do, and then come back to the store. Sure, since they're both Ryobis they do have a lot of things in common, but that doesn't mean you'd ever substitute one for the other.

I won't list every difference, because there's a lot, but, to an approximation, the intersection of their two feature lists looks more-or-less like SML's feature list.