repost:
Actually, the term used was “alternate quantum realities.”
And
GeordiData had a diagram of the time continuum up on the panel when he was trying to explain Worf’s predicament. Here let me find it…Done: https://www.youtube.com/watch?v=MzUEu7Gb7Cg
DATA: I believe the quantum fissure we discovered is a fixed point across the space time continuum. A keyhole which intersects many other quantum realities.
TROI: What do you mean, quantum realities?
DATA: For any event, there is an infinite number of possible outcomes. Our choices determine which outcomes will follow. But there is a theory in quantum physics that all possibilities that can happen, do happen in alternate quantum realities.
WORF: And somehow I have been shifting from one reality to another.
LOOK AT THAT DIAGRAM. That is what the multiverse space-time continuum looks like in Trek. They all exist. When a choice is made—when any action takes place that could have had an alternate outcome—one or more new alternate timelines diverge from that event.
Worf was going from reality to reality. Nero went back in time. Two different things.