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

Yes

The word "maiores" is identical in spelling, grammar, and fundamental meaning across both Brazilian and Continental Portuguese. It functions as the plural form of the adjective "maior" (greater, larger, bigger, or older). The only significant difference lies in pronunciation. In Brazilian Portuguese, the vowels tend to be more open and clearly articulated. In Continental Portuguese, there is a much heavier use of vowel reduction; the "e" in "maiores" is often reduced to a very short, almost silent schwa, making the word sound more clipped.

Brazilian Portuguese (Using "maiores")

1. As crianças maiores podem entrar sem pagar. (Older children can enter without paying.)
2. Eles são os maiores fãs do time. (They are the biggest fans of the team.)
3. Este é o maior desafio que já enfrentei. (This is the biggest challenge I have ever faced.)
4. As cidades maiores costumam ser mais caras. (Larger cities tend to be more expensive.)
5. Tivemos os maiores lucros deste semestre. (We had the biggest profits this semester.)

Continental Portuguese (Expressing the same ideas)

1. As crianças mais velhas podem entrar sem pagar. (Older children can enter without paying.)
2. Eles são os maiores adeptos da equipa. (They are the biggest fans of the team.)
3. Este é o maior desafio que já enfrentei. (This is the biggest challenge I have ever faced.)
4. As cidades de maior dimensão costumam ser mais caras. (Larger cities tend to be more expensive.)
5. Tivemos os maiores lucros deste semestre. (We had the biggest profits this semester.)