Ehem, "correct" spelling? May I remind you that English was invented in England and American spelling only came about because someone was too lazy to learn so wrote his own dictionary. I know kids tried to do that to get around school classes but for an whole nation! Sorry, but it is not correct, it is a different language! p
Sorry, had to make that rant (that's the short version!), and it is UK-IE spelling to be exact as all European articles follow the English used in Europe, not America. "The Union" and "EU" is nothing to do with spelling, it is just has better flow in my opinion. "EU" isn't a very good acronym. -  t: 
It was meant to be inflammatory, but I figured I could get away with a little good-natured ribbing. ) You're right it's not so much spelling, but probably more accurate to compare it to using odd words like "lift", "petrol", "bonnet", and "boot" for the more proper "elevator", "gas", "hood", and "trunk". I've never heard anyone on this side of the pond call it simply "the Union", but that's no doubt because we don't talk about it that much at all. Regardless, it would be quite clear from context that "the Union" == "the European Union".  (talk|contribs)