One small difference: while Chieftec is standing the case on one of the short sides (with a stand), Alienware's Area 51 sits on a long side.
The shape isn't at all conducive to a space-efficient build, if we're honest, but I'll be the first to admit that it can look really, really striking:
If I were into ludicrous rigs, and was indifferent about size, I could see myself actually wanting something like that
But even not feeling that way, I can respect the aesthetics and general design principals of the Area 51 immensely. Save for the front grille pattern they use, it's tastefully futuristic in a way that most "futuristic" cases just aren't.
(And I say that as someone who generally dislikes pretty much anything Alienware makes)