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

Yes

The word "casal" is identical in meaning, grammar, and spelling in both Brazilian and Continental Portuguese. The only difference is the pronunciation of the final "l". In Brazilian Portuguese, the "l" is vocalized, sounding like a "u" ([ka'zaw]). In Continental Portuguese, the "l" is a velarized "l", where the tongue touches the roof of the mouth ([ka'sal]).

Brazilian Portuguese Examples

1. Eles são um casal muito fofo. (They are a very cute couple.)

2. O casal de passarinhos construiu um ninho na árvore. (The pair of little birds built a nest in the tree.)

3. Eu vi um casal de namorados caminhando na praia. (I saw a dating couple walking on the beach.)

4. Aquele casal de médicos é muito famoso aqui. (That pair of doctors is very famous here.)

5. Eles formam um casal muito unido. (They make a very close/united couple.)

Continental Portuguese Examples

1. Eles formam um casal muito elegante. (They make a very elegant couple.)

2. O casal de pombas pousou no telhado da igreja. (The pair of pigeons landed on the church roof.)

3. O casal de turistas perdeu-se nas ruas de Lisboa. (The couple of tourists got lost in the streets of Lisbon.)

4. Um casal de investigadores chegou ao local do crime. (A pair of investigators arrived at the crime scene.)

5. Eles são um casal muito dedicado ao trabalho. (They are a very dedicated couple to their work.)