Maybe because Portuguese has a word for lounge, "salão" (aka salon in English):
This is also the word for hall as in dance hall and concert hall, not really the hallways in our homes that lead to rooms (like sala, and quarto).
Saguão covers lobby, hall, foyer:
While hallway can be corredor, entrada, vestibulo (a place to dress), and even, hall:
Seriously, if you have a question about a word, start exploring it. What you find can be really enlightening and help make connections to the words already learned (in either language). :)
Plus it stands to reason if English has multiple words for something then so does another language. =)