in Spain we may find the word emparedado but bocadillo or sandwich is more used. Normally I'd say that bocadillo uses standard bread where as sandwich uses sliced bread (what we call pan de molde or pan bimbo (since Bimbo is a powerful brand of sliced bread such as Coke is for cola-drinks))
I know this has been said before, but emparedado is an archaic term used in only one place in the world. Most Spanish speakers use bocadillo , for what we call a hero or submarine sandwich, and sándwich for a sandwich made with sliced bread. It would be nice if Duolingo changed this so we don't embarrass ourselves when we go to other countries.
When I started this course 6+ years ago Duolingo was very fond of the word emparedado. A few years ago when Duo had a revision of the course they replaced emparedado with sándwich. I am surprised this sentence has survived. I am doing a (Checkpoint 6) practice right now and it is pulling me these older sentences to practice.
FYI: I have seen the word emparedado only once in a Mexican restaurant in Mexico. It was kind of fancy place. Other that one instance, I have never seen or heard the word emparedado anywhere else.
(Jan 9, 2020)