Have a few of these and not sure if these are from the back of Jello pr Post cereal. I know earlier Post cards had a red oval saying Post on the cards. If anyone is sure which these are please post the answer. Thanks.
The easiest way to differentiate the 1963 Jell-O cards from the nearly identical Post cards is by the red line dividing the stats. On the Jell-O cards the line is shorter and ends close to the stats whereas on the Post cards the line extends almost to the card borders. I think the cards you've pictured are Post because the stat line extends well beyond the stars above the stats. If they were Jell-O cards, I think the red line would end closer, almost even with the stars.
Also the print is smaller on the Jell-O cards and the cards themselves are a bit smaller. The Jell-O cards measure 3-3/8" X 2-1/2", the Post cards are 3-1/2" X 2-1/2". A very slight difference.