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

Yes.

The word "idades" is identical in meaning, spelling, and grammar in both Brazilian and Continental Portuguese. The only difference lies in pronunciation. In Brazil, vowels are generally more open and the syllables are articulated more clearly. In Portugal, unstressed vowels (especially the final 'e') are much more closed, reduced, or even nearly silent, which can make the word sound more "compressed" to a non-native ear.

Brazilian Portuguese Examples

1. As idades dos alunos variam muito nesta sala. (The students' ages vary a lot in this classroom.)
2. Ele estudou as idades da civilização antiga. (He studied the ages of ancient civilization.)
3. As idades de todos os participantes foram anotadas. (The ages of all participants were noted.)
4. É difícil entender idades tão diferentes no mesmo grupo. (It is difficult to understand such different ages in the same group.)
5. As idades de ouro da música brasileira. (The golden ages of Brazilian music.)

Continental Portuguese Examples

1. As idades dos alunos variam bastante nesta turma. (The students' ages vary quite a lot in this class.)
2. Ele estudou as diversas épocas da civilização antiga. (He studied the various eras of ancient civilization.)
3. As idades de todos os participantes foram verificadas. (The ages of all participants were verified.)
4. É difícil lidar com idades tão distintas no mesmo grupo. (It is difficult to deal with such distinct ages in the same group.)
5. As idades de ouro da música portuguesa. (The golden ages of Portuguese music.)