How would you explain American football to an adult who isn’t familiar with it?

I had an epiphany a few years back: Football is trench warfare, hockey is Blitzkrieg. In football, you carefully set all your pieces into place, then go for the Big Push, and see what happens. In hockey, you keep everything in motion, looking for the opening to strike a winning blow; you’ve got a goal in mind, but how you get there is very fluid.