Beyond being set in space I would say they are pretty different. Outer Wilds is set in a single, hand crafted solar system. The planets are kind of "cutesy" and small. Like you can see the curve of the horizon when you are on each planet because they are each designed as spherical levels you are meant to explore most of.

The space flight mechanics are also pure Newtonian physics ala the Expanse, whereas the ships in no man's fly like planes, not rocket ships.

All that said. If you liked No Man's Sky I think there's a decent chance you'll like Outer Wilds.