I don't really use the term speculative fiction and I'd have to go and read up on it to see if it meshes with anything I call soomit else.

Mainly though, I divvy sci-fi up into two basic types - hard and soft, with hard being the spaceships & aliens type and soft being playing with wonky stuff type (usually Earth-bound, but might not be).

Eh. Not any sort of answer to your question, but that's what my brain comes up with right now.