Is the word quarta-feira the same in Brazilian and European Portuguese?

Yes

The spelling, meaning, and grammatical function of "quarta-feira" are identical in both Brazilian and Continental Portuguese. The only difference lies in pronunciation. In Brazil, vowels tend to be more open and the rhythm is syllable-timed, whereas in Portugal, vowels are often more closed or reduced, and the rhythm is more stress-timed. Additionally, while the word itself is the same, the surrounding sentence structure and vocabulary used alongside it often differ between the two varieties.

Brazilian Portuguese Examples

1. Eu tenho aula na quarta-feira. (I have class on Wednesday.)
2. A gente vai ao cinema na quarta. (We are going to the movies on Wednesday.)
3. O ônibus passa aqui na quarta-feira. (The bus passes here on Wednesday.)
4. Você tem algum compromisso na quarta? (Do you have any appointment on Wednesday?)
5. Eu estou estudando para a prova de quarta-feira. (I am studying for Wednesday's exam.)

Continental Portuguese Examples

1. Eu tenho aulas na quarta-feira. (I have classes on Wednesday.)
2. Nós vamos ao cinema na quarta. (We are going to the movies on Wednesday.)
3. O autocarro passa aqui na quarta-feira. (The bus passes here on Wednesday.)
4. Tens algum compromisso na quarta? (Do you have any appointment on Wednesday?)
5. Estou a estudar para o exame de quarta-feira. (I am studying for Wednesday's exam.)