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

Yes

The spelling, meaning, and grammatical function of "alguns" are identical in both Brazilian and Continental Portuguese. The only difference lies in pronunciation. In Brazil, the "s" at the end of the word is typically pronounced as a dental or alveolar [s] (similar to the "s" in "sun"), whereas in Portugal, it is often pronounced as a postalveolar [ʃ] (a "sh" sound, as in "shoe"). Additionally, the vowels in Brazil tend to be more open, while in Portugal, they are often more closed or reduced.

Brazilian Portuguese Examples

1. Alguns amigos vão participar da festa. (Some friends are going to participate in the party.)
2. Eu comprei alguns livros ontem. (I bought some books yesterday.)
3. Alguns dias são mais difíceis que outros. (Some days are harder than others.)
4. Tem alguns problemas para resolver. (There are some problems to solve.)
5. Alguns alunos não entenderam a matéria. (Some students didn't understand the subject.)

Portuguese (Continental) Examples

1. Alguns amigos vêm à festa. (Some friends are coming to the party.)
2. Comprei alguns livros ontem. (I bought some books yesterday.)
3. Alguns dias são mais difíceis do que outros. (Some days are harder than others.)
4. Há alguns problemas para resolver. (There are some problems to solve.)
5. Alguns alunos não perceberam a matéria. (Some students didn't understand the subject.)