There are a lot of differences between sports fans here in America and over in England. For instance, when Americans run onto the court or field, they’re usually doing it to celebrate the home team’s victory. When the English do it, they’re generally running onto the pitch with the intentions of murdering either a player or a referee. It’s a subtle difference, sure, but it’s rather important.
Of course, security in both countries differs, as well. Where as here in the States they generally perform full cavity searches to make sure you’re not sneaking in a half-pint of Jack Daniels, in England they’re more concerned with keeping you off the field or rioting, so you can bring more stuff into the stadium with you. Could you imagine bringing your parrot with you in a cage while going to see a Pirates game? There’s no way in hell they’d let you do that, but in England it’s cool. It also leads to trouble.