It’s certainly interesting and to be perfectly honest If you compare the body of Davis Prowse with Sebasitian Shaw.

Davis Prowse had a lot of muscle and was a much larger build.

Sebastian Shaw looks plump and fat comparitively.

It’s not so much the face but the actual build of the man it’s actually pretty obvious it’s a different person when Sebastian Shaw is a force ghost… But I guess it can be explained away by Vaders replacement Robot Body parts so it does not really create an issue

Davis Prowse is also quite a bit taller which is another problem that sebastian Shaw obviously is not Vader as he Looks Stunted as a force ghost.

Was’nt the make up shot of Prowse back of his head for Empire Strikes Back and not Return of Jedi?