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

Yes

The word nessas is a contraction of the preposition em (in, on, or at) and the demonstrative pronoun essas (these or those—feminine plural). There are no differences in meaning, spelling, or grammatical function between Brazilian and Continental Portuguese. The only difference is pronunciation: in Brazil, the "s" at the end of the word is typically pronounced as a soft "s" (as in "sun"), whereas in Portugal, the "s" is pronounced as a "sh" sound (as in "shoe").

Brazilian Portuguese Examples:

1. Não acredito nessas histórias. (I don't believe in those stories.)
2. Você viu as mudanças nessas fotos? (Did you see the changes in these photos?)
3. Não coloque as chaves nessas caixas. (Don't put the keys in these boxes.)
4. A gente sempre se perde nessas conversas. (We always get lost in these conversations.)
5. O que aconteceu nessas reuniões? (What happened in these meetings?)

European Portuguese Examples:

1. Não acredito nessas histórias. (I don't believe in those stories.)
2. Viste as alterações nessas fotografias? (Did you see the changes in these photos?)
3. Não ponhas as chaves nessas caixas. (Don't put the keys in these boxes.)
4. Nós sempre nos perdemos nessas conversas. (We always get lost in these conversations.)
5. O que aconteceu nessas reuniões? (What happened in these meetings?)