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

Yes.

The meaning, spelling, and grammar of "sexto" are identical in both Brazilian and European Portuguese. The only difference lies in pronunciation. In Brazilian Portuguese, the vowels are typically more open and the rhythm is more "syllable-timed," making the final "o" clearly audible as a /u/ sound. In European Portuguese, the rhythm is more "stress-timed," and unstressed vowels are heavily reduced, meaning the final "o" in "sexto" is much shorter and often almost swallowed.

Brazilian Portuguese Examples:

1. Eu moro no sexto andar. (I live on the sixth floor.)
2. Ele ficou em sexto lugar na competição. (He finished in sixth place in the competition.)
3. Este é o nosso sexto encontro do ano. (This is our sixth meeting of the year.)
4. O sexto aluno da lista foi chamado. (The sixth student on the list was called.)
5. Ele é o sexto da fila. (He is the sixth in line.)

European Portuguese Examples:

1. Eu moro no sexto andar. (I live on the sixth floor.)
2. Ele ficou em sexto na competição. (He finished sixth in the competition.)
3. Este é o nosso sexto encontro do ano. (This is our sixth meeting of the year.)
4. O sexto aluno da lista foi chamado. (The sixth student on the list was called.)
5. Ele é o sexto da fila. (He is the sixth in line.)