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

Yes

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

In Brazilian Portuguese, the vowels tend to be more "open" and the rhythm is more syllable-timed, making the "e" and the nasal "ão" sound very clear and resonant. In Continental Portuguese, the pronunciation is more "closed" due to heavy vowel reduction; unstressed vowels are often swallowed or shortened, making the word sound more clipped and less melodic to Brazilian ears.

Brazilian Portuguese Examples

1. Preste atenção ao que eu estou dizendo. (Pay attention to what I am doing/saying.)
2. Ele trabalha com muita atenção. (He works with a lot of care/attention.)
3. Muita atenção com o degrau! (Be very careful with the step!)
4. O professor pediu atenção de todos os alunos. (The teacher asked for the attention of all students.)
5. Atenção, o ônibus está chegando. (Attention, the bus is arriving.)

Continental Portuguese Examples

1. Presta atenção ao que eu estou a dizer. (Pay attention to what I am saying.)
2. Ele trabalha com muita atenção. (He works with a lot of care/attention.)
3. Cuidado com o degrau! (Watch out for the step!)
4. O professor pediu a atenção de todos os alunos. (The teacher asked for the attention of all students.)
5. Atenção, o autocarro está a chegar. (Attention, the bus is arriving.)