Experienced 2 uniquely British experience while I was in London - Wimbledon and Premier League.
Here are some differences I spotted...
1) Football fans are watched predominantly by males and Wimbledon fans are quite equally spread among both sexes. Also, the females watching Wimbledon are generally prettier than the average girl on the street. Even the people working in Winbledon are hot! Not too sure about the people working at football matches though.
2) Football fans are predominantly from the middle and lower class of society while people who attend Wimbledon are generally at the upper echelon of society --> Football is for the masses and tennis is for the blue-blooded.
3) Football fans are much more rowdier/uncivilised compared to Wimbledon fans. That explains why after a match, the football stadium is in a much dirtier state than the tennis stadium.
4) Attending a football match is attending a football match, with the occassional brawl; attending Wimbledon feels much more like attending a carnival, with many other activities to keep you occupied in between matches.
But despite all the differences, rubbish food and alcohol is available at both events in bountiful supply.