Answer:
departamento
Step-by-step explanation:
"Apartamento" and "departamento/ are synonym words for "apartment".
The different lies in which country it's used. Spanish varies a lot from on Spanish-speaking country to the other... and the variations will be like this one, where on word is used instead of another to identify the same concept.
Like in Mexico they'll use "durazno" for "peach", while in Guatemala, they'll use "melocoton".
Some words change more than others... like I've encountered at least a half-dozen different words for "popcorn", depending on the country.