@ehBeth,
Yes, I remember reading up on football's history in North America decades ago. In the early 20th century, college sports were not organized into conferences and leagues. Teams made arrangements to play each other on their own. Things at this stage were so informal that when the two teams met, before the game they agreed on the ground rules-number of downs, (3, 4, 5?), length of the field, etc. Northern USA colleges frequently played Canadian colleges at this stage.
As the game caught on, more colleges started playing and also started conferences, so the inter-country play stopped. Each country's conferences and leagues codified their rules by their respective ruling bodies, and no effort was to made to standardize the rules between the countries. With no money in it back then, there was no compelling reason to do this. So the rules these days are slightly different, but the game developed in both countries at the same time.