Maybe it's just me, but it does seem like there's a better term waiting to be discovered for this than "tech tree". (I can't exactly tell, but it seems like you wouldn't mind a better term either).

Not a fan of "worlds" as proposed below. I have a feeling we're all just projecting our own favorite genre conventions here, but your different approaches remind me of different characters more than anything else. Ever play a game where you had a choice of approaches with different characters? Or had to switch between them and coordinate action or share information?

I'm sure there's plenty of people who possess the union of these skill sets (and of course, there will be plenty of actual human players that will), but you could describe your trees more as character growth/background/capabilities/backstory.

You would then have interesting story possibilities here—I would love the idea but I suspect you guys might consider story elements as potentially distracting.