Furball, the folks in Mexico call it "Spanish." The folks in Spain call it "Spanish." The folks in USA call it "English." The folks in England call it "English."
It's just the name, doesn't mean it's the exact same language

As you can see there are things you can say in England that a Yank wouldn't be able to follow at all.
I believe the difference between Spain/CentralAmerica is more than that, down to the way certain things are prononuced and spoken. More of a different language, but carries the same name. At least that's how a Spanish teacher explained it to me once.