Are the various engines (eg query optimizer, storage engine, etc) the same in all editions (eg Standard, Enterprise), and simply have certain capabilities enabled or disabled? Asking because a contractor is trying to tell us that the Enterprise query optimizer is better/faster than the Standard optimizer. I have been searching/googling on this issue, and have not seen anything clearly saying so one way or the other.

I understand that new versions are faster than old versions, for example 2008 is faster than 2000. Just asking whether, within a single version, if the editions are all using the same engines.