It's hard to know which word should be used in which country.
Some countries use only one term, some others use 2 or 3 with different meanings, and some other ones give one of the terms another meaning or even the opposite meaning.
It becomes very hard to understand.
I already know that "sándwich" is used in Spain (and in most countries), but not "emparedado".
In Spain, it seems that they have the two words "sándwich" and "bocadillo", but not with the same kind of sandwich -- so what's the difference and how did it come about, etymologically?
There's also "sanduche", "sanguche" (Guatemala, Argentina), "sangüich", etc.