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

No

Differences

• Grammar: The primary difference lies in the continuous/progressive aspect. In Brazil, the gerund is used (e.g., treinando). In Portugal, the construction "a" + infinitive is used (e.g., a treinar).
• Usage and Vocabulary: In Brazil, treinar is frequently used as a synonym for "working out" or "lifting weights" (often alongside the word malhar). In Portugal, while treinar is used for sports, the phrase fazer exercício is more common for general fitness. Furthermore, the surrounding vocabulary typically changes, such as academia (BR) vs. ginásio (PT) and cachorro (BR) vs. cão (PT).

Brazilian Examples

1. Eu estou treinando muito hoje. (I am training/working out a lot today.)
2. Ele treina futebol toda semana. (He practices football every week.)
3. Você treina na academia? (Do you work out at the gym?)
4. Nós estamos treinando o cachorro. (We are training the dog.)
5. Ela treina para a maratona. (She is training for the marathon.)

Portuguese Examples

1. Eu estou a treinar muito hoje. (I am training/working out a lot today.)
2. Ele treina futebol todas as semanas. (He practices football every week.)
3. Tu treinas no ginásio? (Do you work out at the gym?)
4. Nós estamos a treinar o cão. (We are training the dog.)
5. Ela treina para a maratona. (She is training for the marathon.)