To begin with the balls are entirely different. A soccer ball is a sphere while a football is an ellipsoid. There are very few pauses in soccer. Soccer players wear little protective equipment compared to football players. There are no wholesale substitutions from offense to defense and back in soccer as there are in football. Points are scored one at a time in soccer. Many more countries play soccer than play football.
There is much less equipment in soccer. soccer has 11 players on the field, no time outs (except for quarters or halves), & just laws of the game. the biggest difference is advantage play on law.
In soccer you can't touch the ball but in football you can.
Soccer players are very agile, quick, and very well conditioned since they must play long periods with no rest. Football players tend to be much more powerful and larger since they are playing a game based on sheer power. They are also well conditioned athletes but their conditioning is oriented toward a different outcome.