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

Yes

The word "minhas" is identical in meaning, grammar (feminine plural possessive), and spelling in both Brazilian and Continental Portuguese. The differences are found in:

• Pronunciation: In Portugal, the "s" at the end of the word is typically pronounced as a "sh" sound ([ʃ]), and the unstressed vowels are more closed or reduced. In Brazil, the "s" is generally more sibilant ([s]), and the vowels are more open and clearly articulated.
• Syntactic Environment: While the word itself remains the same, the typical usage surrounding it differs. In Portugal, it is standard to use a definite article (as) before a possessive adjective (e.g., "as minhas"), whereas, in Brazil, it is common and natural to omit the article (e.g., "minhas").

Brazilian Portuguese Examples

1. Minhas chaves sumiram. (My keys disappeared.)
2. Minhas amigas são muito legais. (My friends are very cool.)
3. Minhas roupas estão no armário. (My clothes are in the closet.)
4. Minhas plantas estão crescendo rápido. (My plants are growing fast.)
5. Onde estão minhas canetas? (Where are my pens?)

Portuguese (Continental) Examples

1. As minhas chaves desapareceram. (My keys disappeared.)
2. As minhas amigas são muito fixes. (My friends are very cool.)
3. As minhas roupas estão no roupeiro. (My clothes are in the wardrobe.)
4. As minhas plantas estão a crescer rápido. (My plants are growing fast.)
5. Onde estão as minhas canetas? (Where are my pens?)