You can go to the store and hold both in your hands. The NFL is bigger.
Also, there is no uniform NCAA ball. There are certain measurements that balls have to meet but they can vary.
You can buy a Wilson ball that is slightly wider or more narrow. I think the 1001 is the wider and most commonly used. The 1005 is a little more narrow IIRC.
The Nike ball was more narrow the thr Addidas ball.
There is also that orange looking ball put out by Wilson that is more taken the. The leather.