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

Yes

The word "irmã" is identical in meaning, spelling, and grammatical function in both Brazilian and Continental Portuguese. The differences are strictly phonetic:

• Vowel Openness: Brazilian Portuguese tends to have more "open" vowels. In the word "irmã," the nasalized "ã" is pronounced with a clearer, more open resonance. In Continental Portuguese, unstressed vowels are often "reduced" or closed, making the word sound more clipped.
• The "r" sound: Depending on the region of Brazil, the "r" in "ir" may be pronounced as a retroflex (like the American English "r") or a soft tap. In Portugal, the "r" is typically an alveolar tap or a more distinct friction sound.
• Rhythm: Brazilian Portuguese is more syllable-timed, giving each syllable a more even weight. European Portuguese is stress-timed, which often causes the unstressed "i" in "irmã" to be swallowed or shortened significantly.

Brazilian Portuguese Examples

1. Minha irmã é muito legal. (My sister is very cool.)
2. Eu vou sair com a minha irmã hoje. (I am going out with my sister today.)
3. Minha irmã mais velha mora em São Paulo. (My older sister lives in São Paulo.)
4. Você tem alguma irmã? (Do you have any sisters?)
5. A minha irmã é médica. (My sister is a doctor.)

Continental Portuguese Examples

1. A minha irmã é muito gira. (My sister is very pretty/nice.)
2. Vou sair com a minha irmã hoje. (I am going out with my sister today.)
3. A minha irmã mais velha vive em Lisboa. (My older sister lives in Lisbon.)
4. Tens alguma irmã? (Do you have any sisters?)
5. A minha irmã é médica. (My sister is a doctor.)