Let's take a step back in time from the last post; where it was one of the earliest compiles of Vista, this build below is the very first compile of Vista after the reset. In fact, it is so similar to Server 2003 (because it literally IS the same code) that even the theming service is disabled by default.
There is only one way to tell that this build is a Longhorn build, and that is the EULA as pictured below. Other differences are zero-day activation : you must activate the build before you can log on. This is the earliest possible look at Vista and shows how far they had to go to get back on track once they reset the project.