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

Yes

The word "são" is identical in meaning, spelling, and grammar in both Brazilian and European Portuguese. The only difference is pronunciation. In Brazilian Portuguese, the nasalized vowel "ã" is typically more "open" and resonant. In European Portuguese, vowels—especially nasalized ones—tend to be more "closed" or reduced, which often makes the word sound more clipped or subtle to the ear.

Brazilian Portuguese Examples

1. Eles são muito legais. (They are very cool.)
2. São muitas pessoas no ônibus. (There are many people on the bus.)
3. Eles são meus amigos. (They are my friends.)
4. Esses meninos são espertos. (Those boys are smart.)
5. Eles são muito bons jogadores. (They are very good players.)

European Portuguese Examples

1. Eles são muito fixes. (They are very cool.)
2. São muitas pessoas no autocarro. (There are many people on the bus.)
3. Eles são os meus amigos. (They are my friends.)
4. Esses rapazes são espertos. (Those boys are smart.)
5. Eles são muito bons jogadores. (They are very good players.)