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

Yes

The word "guerra" is identical in spelling, meaning, and grammar in both Brazilian and Continental Portuguese. The only difference lies in pronunciation. In Brazilian Portuguese, the vowels tend to be more open and the "rr" is typically pronounced as a strong, aspirated sound (similar to the English "h" in "house"). In Continental Portuguese, the vowels are often more "closed" or reduced, and the "rr" is pronounced with a more distinct fricative sound, often deeper in the throat.

Brazilian Portuguese Examples

1. A guerra entre os dois países é preocupante. (The war between the two countries is worrying.)
2. Eles declararam guerra ao sistema. (They declared war on the system.)
3. A guerra comercial está afetando a economia. (The trade war is affecting the economy.)
4. Ninguém quer uma guerra nuclear. (No one wants a nuclear war.)
5. Essa guerra de preços é muito agressiva. (This price war is very aggressive.)

Continental Portuguese Examples

1. A guerra causou muitos danos materiais. (The war caused much material damage.)
2. O país encontra-se em guerra. (The country is at war.)
3. É necessário evitar a guerra a todo o custo. (It is necessary to avoid war at all costs.)
4. A guerra civil foi um período muito triste. (The civil war was a very sad period.)
5. Eles vivem em constante guerra. (They live in constant war.)