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

No

While the word "estão" is identical in spelling, meaning, and grammatical category (3rd person plural of the verb estar) in both dialects, there is a difference in typical usage and pronunciation:

• Usage: In Brazilian Portuguese, "estão" is typically followed by the gerund to express ongoing actions (e.g., estão fazendo). In Continental Portuguese, "estão" is typically followed by the preposition "a" + the infinitive of the verb (e.g., estão a fazer).
• Pronunciation: In Brazil, the nasal diphthong "ão" tends to be pronounced with a more open and distinct resonance. In Portugal, the pronunciation can be more closed or subtle, depending on the regional accent.

Brazilian Portuguese Examples

1. Eles estão muito felizes hoje. (They are very happy today.)
2. As chaves estão em cima da mesa. (The keys are on top of the table.)
3. Meus amigos estão chegando agora. (My friends are arriving now.)
4. Onde estão os meus documentos? (Where are my documents?)
5. Eles estão estudando para a prova. (They are studying for the exam.)

Continental Portuguese Examples

1. Eles estão muito felizes hoje. (They are very happy today.)
2. As chaves estão em cima da mesa. (The keys are on top of the table.)
3. Os meus amigos estão a chegar agora. (My friends are arriving now.)
4. Onde estão os meus documentos? (Where are my documents?)
5. Eles estão a estudar para o exame. (They are studying for the exam.)