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

Yes

The word "amiga" is identical in spelling, meaning, and grammatical function in both Brazilian and Continental Portuguese. The only difference is in pronunciation.

In Brazilian Portuguese, the vowels are generally more "open" and the rhythm is more syllable-timed, meaning each syllable is given a relatively equal duration. In Continental Portuguese, unstressed vowels are often "closed" or reduced (sometimes becoming almost silent), and the rhythm is more stress-timed, which creates a more "clipped" or consonant-heavy sound.

Brazilian Portuguese Examples:

1. "Ela é minha melhor amiga." (She is my best friend.)
2. "Oi, amiga! Tudo bem?" (Hi, friend! How are you?)
3. "Vou sair com uma amiga hoje." (I am going out with a friend today.)
4. "A minha amiga mora aqui perto." (My friend lives near here.)
5. "Você é uma amiga fantástica." (You are a fantastic friend.)

Continental Portuguese Examples:

1. "Ela é a minha melhor amiga." (She is my best friend.)
2. "Olá, amiga! Como estás?" (Hello, friend! How are you?)
3. "Vou sair com uma amiga hoje." (I am going out with a friend today.)
4. "A minha amiga vive aqui perto." (My friend lives near here.)
5. "És uma amiga fantástica." (You are a fantastic friend.)