Dietro / behind is a preposition and an adverb in both languages. If we want to be more precise, dietro can be a pronominal adverb as well, can stand for something.
prepositions
Dietro la casa c'è un giardino.
Behind the house there is a garden.
Siamo andati dietro la casa.
We went behind the house.
adverb
Non c' è niente dietro.
There is nothing behind.
But in both languages there is a difference between a movement and the description of the relationship between two objects in space.
Go back!
Vai indietro!
To describe a movement, we use indietro and not dietro.
