There was a big shift between Super Metroid and Metroid Fusion. Compared to Zero Mission, there is almost no plot in Super Metroid. The only major plot point is the whereabouts of the metroid which Ridley abducted in the opening scene.

Super Metroid is much more action focused then the later entries. I will say that the later areas are a little more atmospheric than the first half of the game. Wrecked Ship definitely has a different vibe than the rest.

I’d say it’s okay to take a break from Super Metroid and try Fusion. Fusion is much more linear and story driven. There was a short Super Metroid comic series in Nintendo Power that might provide some more context.