The cheaper Enterprise is a Tamiya knockoff. The over all quality matches the cheap price. The plastice is softer, the detailing is not as crisp as Tamiya. I picked one up a couple of years ago and ended up giving it to my son when I did a side by side with the Tamiya Enterprise.
One other thing, it's not an Academy release. It's from a company called Mini Hobby Craft. Their prices are cheaper and so it the quality of their products!