I don't know about in Brazil or Portugal, but there's something of a distinction in the US. A popular person has all the makings of a famous person usually, they're charming or talented, but they might not be known for anything particular. And likewise a famous person may fall out of favor, losing their popularity, but they're still famous because they're recognizable.
Famous & Popular: World famous Pop Star
Just Famous: Disgraced athlete
Just Popular: Attractive or funny classmates