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

No.

While the spelling, meaning, and grammar of "quinta-feira" are identical in both varieties, there are differences in pronunciation and typical usage:

• Pronunciation: Brazilian Portuguese tends to have more open vowels and a syllable-timed rhythm, making each syllable more distinct. In Continental Portuguese, vowels are often much more closed or reduced (the "e" in "feira" is often nearly silent), and the rhythm is more stress-timed.
• Usage: In Brazil, the word is typically used with the preposition "na" (em + a). In Portugal, it is very common to use the preposition "à" (a + a) when referring to that day.

Brazilian Portuguese Examples

1. Eu tenho aula na quinta-feira. (I have class on Thursday.)
2. O jantar será na quinta-feira. (Dinner will be on Thursday.)
3. Você vai à academia na quinta-feira? (Are you going to the gym on Thursday?)
4. Na quinta-feira, eu estudo muito. (On Thursday, I study a lot.)
5. O médico atende na quinta-feira. (The doctor sees patients on Thursday.)

Continental Portuguese Examples

1. Eu tenho aula à quinta-feira. (I have class on Thursday.)
2. O jantar será na quinta-feira. (Dinner will be on Thursday.)
3. Vais ao ginásio à quinta-feira? (Are you going to the gym on Thursday?)
4. À quinta-feira, eu estudo muito. (On Thursdays, I study a lot.)
5. O médico atende na quinta-feira. (The doctor sees patients on Thursday.)