No, there was never a difference in the football size or regulations between the AFC and NFC. This would be too hard to regulate since the AFC and NFC teams play each other so often.
I believe it's from the merge between the AFL and NFL the AFC teams are the American football league teams and the NFC the national football league.
AFC- AFC east, AFC west, AFC north, AFC south NFC- NFC east, NFC west, NFC north, NFC south
The first pro bowl between AFC and NFC was January 21, 1973.
The NFL Divisions are NFC North NFC South NFC East NFC West AFC North AFC South AFC East AFC West
what does it means if the winner of the AFC and NFC means
Nfc 34, AFC 41