In England, I am told, they play or used to play two kinds of football: "Rugby football" or "rugger" and "Association football" or "soccer."
In the United States, we play variations of both games, but, for whatever historical reasons, Rugby football became so much more popular than soccer that to us, it is just "football." We didn't need to call it "Rugby football" because it was the almost the only kind of "football" there was.
When I was in high school during the 1960s, the high school football team was very important--the most important of all school teams. They played against other teams and marched onto the field with the high school band playing the "fight song" and all the rest of it.
There was no soccer team at all. One of the coaches started to offer informal after-school soccer games. The teams were picked from whomever showed up. The school didn't have any real soccer balls, so we played with red rubber playground balls. That shows you the difference in popularity between "football" and "soccer" back then.
Soccer is much more popular today, and with our respectable showing in the Olympics it will probably become even more popular, but it's still not one of the "big" sports.