vs
QUICK ANSWER
"Detrás de" is a preposition which is often translated as "behind", and "al lado" is a phrase which is often translated as "nearby". Learn more about the difference between "detrás de" and "al lado" below.
detrás de()
A preposition is a word that indicates the relationship between a noun and another word (e.g., He ran through the door.).
al lado()
A phrase is a group of words commonly used together (e.g., once upon a time).