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

Yes.

The spelling, meaning, and grammatical function of "comprei" (the first-person singular indicative preterite of the verb comprar) are identical in both Brazilian and Continental Portuguese. The only difference lies in pronunciation. Brazilian Portuguese tends to have more open, clearly articulated vowels, whereas Continental Portuguese features vowel reduction, where unstressed vowels are often shortened or "swallowed," creating a more stress-timed rhythm.

Brazilian Portuguese Examples

1. Comprei um celular novo ontem. (I bought a new cell phone yesterday.)
2. Comprei um sorvete de chocolate. (I bought a chocolate ice cream.)
3. Comprei uma passagem de ônibus. (I bought a bus ticket.)
4. Comprei um lanche na padaria. (I bought a snack at the bakery.)
5. Comprei um brinquedo para o meu filho. (I bought a toy for my son.)

Portuguese (Portugal) Examples

1. Comprei um telemóvel novo ontem. (I bought a new mobile phone yesterday.)
2. Comprei um gelado de chocolate. (I bought a chocolate ice cream.)
3. Comprei um bilhete de autocarro. (I bought a bus ticket.)
4. Comprei um lanche na pastelaria. (I bought a snack at the pastry shop.)
5. Comprei um brinquedo para o meu filho. (I bought a toy for my son.)