History: Football vs. Soccer
Football is actually a relative from soccer. Though the date is unsure of when the sport was first known to be played, there were many professional teams starting to spring up in the late 1800s. It was not that much different from its closer cousin rugby, but was showing some far different plays from soccer already.
Here is an interesting fact. Soccer or "football" as is as known in most European and South American Countries is actually the founder of both rugby and football. The major disconnections occurred when the rules for soccer changed to a "no hands" rule. At this point rugby was born. Later as rugby split into two different kinds of play: traditional rugby which allows drop kick goals and more footwork, and American football which has kickoffs and field goals (reminiscent of its soccer days) tackling and hand offs (similar to rugby) and forward passing, options, and other additions.
Soccer on the other hand has a long history, according to the Munich Ethnological Museum there is a Chinese text dated around 50 B.C. talking about "soccer" games in china. Though it is unsure how similar these games were to what we know as soccer today.
Team Size: Football vs. Soccer
There is a tremendous size difference between football and soccer. In football you not only have players that make up a team, but you have specific teams within your team. There are three major teams that consist of a football team: The offense, the defense, and special teams. Each one has a specific objective. The offense with a quarterback, receivers, and guards' objective are to score touchdowns, while the defensive team's job is to stop the opposing team from scoring by tackling the quarterback, runners, or blocking passes. Special teams deal with punts, field goals, and kickoffs. All in all there are anywhere from 30 - 60 players that combine to make a football team.
Soccer is a continuous sport. Meaning unlike football where you have set plays and an offensive and defensive team, in soccer the ball is always going. That being the case there are still offensive and defensive parts to the play of soccer. One can tell whether a team is on the offensive or defensive by where the ball is on the field. If the ball is on your side of the field then you are on defensive, if it is on your opponent's side then you are on the offensive.
Fan Size: Football vs. Soccer
Determining which sport has a greater or more loyal fan base is difficult. Here in the United States American football by far has the larger fan base. However, outside of the United States (and perhaps Canada) you do not hear much about football, only soccer. Entire cities have been known to shut down for the world cup, and yet the most watched event was last year's super bowl. One thing is a fact. Both soccer and football have loyal fans that are not going anywhere.
Conclusion
Soccer or Football? Well when it comes right down to it, you are choosing between two very popular sports that will continue to gain momentum in the years to come.