Hopefully, you won't mind if I provide a few constructive comments about your work...
Overall, these helmets are pretty good. I'll admit that I'm disappointed in the helmet for my favorite team - the Kansas City Chiefs. The Arrowhead logo is too small (and thin) - as it relates to the overall size of the helmet and also when compared to the logos of other teams.
I would encourage you to double-check the angle (and location) of each team's logo. Some of them are off a bit. For example, the Eagles "wings" logo should join together more towards the front/center of the helmet (where the "Riddell" logo piece is located). The Patriots logo should be smaller in size and moved higher and farther back.
With regard to other logos, several are over-rotated and need to be leveled a bit. The Lions logo should be slightly leveled and moved farther ahead. The Cowboys "Star" logo should be level - exactly straight up and down - not slanted towards the back of the helmet.
Additionally, the white plastic piece on the front of the helmets (used for the "Riddell" logo) is too large. If you look at the modern helmets worn by today's NFL players, that piece is pretty small - only slightly bigger than the "Riddell" lettering.
Lastly, the face masks are too large and shouldn't cover the ear holes.
Please don't misinterpret my comments about your work as being negative in any way. They're only being provided as constructive criticism. I have no clue whether or not you created these helmets from "scratch" or if you had to use graphics acquired from another source. Some of the items I mentioned may very well be out of your control.
I like what you've done and I appreciate your willingness to share it with all of us.
Thank you for the critique and all though I didn't ask for one I really do appreciate it. I will fix the noted errors when time permits. They were made from scratch so I do have the vectored layers to do so. Thanks again!
Here is what I have found to answer your question. Hope this helps.
"originally there was only one football league in the us but then a new league was created which included new teams like the patriots and the broncos. the original league was called the national football league and the new league was called the American football league. later they were changed to conference instead of league. other wise there is no difference between AFC and NFC."