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

Yes

The word "aventura" is identical in spelling, meaning, and grammatical function in both Brazilian and European Portuguese. The only difference lies in pronunciation:

• Brazilian Portuguese: The vowels tend to be more "open" and clearly articulated. The unstressed "e" in the middle of the word is usually audible and pronounced clearly. The rhythm is more melodic and syllable-timed.
• Continental Portuguese: The vowels are more "closed" and subject to significant reduction. In many regions of Portugal, the unstressed "e" in "aventura" may become almost silent or reduced to a very short, neutral sound, making the word sound more "compressed."

Brazilian Portuguese Examples

1. Eu adoro viver uma aventura nova todo ano. (I love living a new adventure every year.)
2. Essa viagem para a Amazônia foi uma aventura inesquecível. (That trip to the Amazon was an unforgettable adventure.)
3. Ele está sempre procurando uma aventura no fim de semana. (He is always looking for an adventure on the weekend.)
4. Que aventura foi subir aquela trilha no calor! (What an adventure it was to climb that trail in the heat!)
5. Não quero me meter em nenhuma aventura perigosa. (I don't want to get myself into any dangerous adventure.)

European Portuguese Examples

1. Adoro viver uma aventura nova todos os anos. (I love living a new adventure every year.)
2. Esta viagem para a Amazónia foi uma aventura inesquecível. (This trip to the Amazon was an unforgettable adventure.)
3. Ele procura sempre uma aventura ao fim de semana. (He always seeks an adventure on the weekend.)
4. Que aventura foi subir aquela trilha no calor! (What an adventure it was to climb that trail in the heat!)
5. Não quero meter-me em nenhuma aventura perigosa. (I don't want to get myself into any dangerous adventure.)