A) I would say the MSI is. The cpu may be slightly worse, but it has double the ram, a better gpu, and a larger hard drive.
B) I don't see how it would, if the MSI offers better performance right now. As far as reliability, I have never had experience with MSI laptops, but I think they are both good/decent brands.
That being said, why did you order the Alienware when you had the MSI already? I don't mean to sound rude, I just don't understand the point to having two laptops that are similar in performance. Also, where did you order the alienware from? Its processor is a last generation one and I didn't think Dell even made them/had them available to order on their website anymore.