I ordered CMA's Big Blue towel a couple days before 4 Star Platinum signed on as a sponsor of Autopia. Someone brought up that they have a Big Blue towel just like CMA does. Being the "need to know" kind of guy that I am, I bought one to test against CMA's. I have them both together today and have some visual comparison pictures to show you. Actual field testing will take place later.
CMA on the left and 4 Star on the right. Fluffy test. CMA on the left and 4 Star on the right. Weave comparison. CMA on the left and 4 Star on the right. Another weave comparison. CMA on the right and 4 Star on the left. Slight size difference. 4 Star on top of CMA. Pepsi cans are the only way we measure things in my house. 
I'll do some more testing on vehicles very soon. I just thought I'd get some photos up first.
The CMA towel is definatly heavier. It is my prediction that it will absorb much better. However, the 4 Star towel is very very soft and kinda elasticy. I think its water retention qualities might shock us a little. I'll get them tested as soon as I can.
edit: I almost forgot. The CMA towel is 80/20 Polyester/Polyamide and the 4 Star towel is 70/30. That may account for the fluffy factor.
edit #2: Direct links to
4 Star's Big Blue Towel and
CMA's Big Blue Towel