SpaceX Raptor Engines

SpaceX Raptor Rocket Engines
Engine for atmospheric operation on the left
Engine for vacuum operation on the right

This picture shows how much bigger the nozzle on the vacuum engine is. The mechanical bits at the top are very similar, if not identical.


How SpaceX's New Raptor Vacuum Engine Is Different From Previous Raptors (and Other Stuff)
Scott Manley

In this video Scott Manley gives a pretty good explanation of the issues involved in designing rocket engine nozzles for different conditions.