Is the word boas the same in Brazilian and European Portuguese?

No.

The difference between the two dialects lies in typical usage. In Continental Portuguese (Portugal), "Boas!" is a very common, informal, and gender-neutral way to say "Hi" or "Greetings" (acting as a shorthand for boas tardes or boas noites). In Brazilian Portuguese, "Boas" is almost never used as a standalone greeting; it is used almost exclusively as the feminine plural of the adjective boa (good) or as the noun boa (the boa constrictor snake).

Brazilian Portuguese Examples

(Using "boas" as an adjective)

1. Recebi boas notícias hoje. (I received good news today.)
2. Ela sempre tem boas ideias. (She always has good ideas.)
3. Tivemos boas experiências na viagem. (We had good experiences on the trip.)
4. Desejo a todos boas festas! (I wish everyone happy holidays!)
5. Essas são boas escolhas para o projeto. (These are good choices for the project.)

Portuguese Examples

(Expressing the same ideas)

1. Recebi boas notícias hoje. (I received good news today.)
2. Ela sempre tem boas ideias. (She always has good ideas.)
3. Tivemos boas experiências na viagem. (We had good experiences on the trip.)
4. Desejo a todos boas festas! (I wish everyone happy holidays!)
5. Essas são boas escolhas para o projeto. (These are good choices for the project.)