RHEL Developers programme and Cent OS

I am using RHEL developers free subscription on 1 machine and Cent OS on the other. My experience has almost been the same. Why I would prefer Dev subscription over Cent OS, Cent OS gives me commercial access too. Yes, there are things like Red hat developer studio and open shift but I can download them on Cent OS and sign in with my Red hat ID. The only difference i do find is Cent OS releases are 1 month after RHEL release and RHEL developer subscription does not provide commercial access, Cent OS does. I can use Cent OS and access customer portal by having RHEL subscription. I get advantage of Customer portal support and also with Cent OS commercial use is allowed. So what is the difference ?