Here is a side by side comparison between the 1963 Topps football and baseball cards. In 1963 Topps produced football cards for the NFL while the AFL appeared on Fleer cards
Fleer also began making cards of current baseball players in 1963 only to be halted after only 66 cards. Ron Santo was one of the players to appear in that set. So we have the opportunity to view them side by side as well.