Open Question: I was wondering what is a "UK Single" exactly?

For example when an American band says "Our UK Single......" Does this mean they'll only be a single in that country or is there's going to be a UK single and a US Single? There's this band that just got signed to B-Unique records over in the UK, I think they're really good, unique kinda. They're called 'Millionaires' if anyone cares or knows about things like this check them out at www.myspace.com/millionaires and tell me what you get. :]