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

No

The difference lies in usage and grammatical construction. While the spelling and basic meaning are identical, "estás" is the standard way to address someone informally in Portugal. In most of Brazil, "estás" is largely regional (common in parts of the South, North, and Northeast) or used in formal/literary contexts; in the majority of Brazil, the 3rd person "está" (paired with você) is the standard. Furthermore, when describing an ongoing action, Brazilians use the gerund (e.g., estás comendo), whereas Portuguese people use the preposition "a" followed by the infinitive (e.g., estás a comer).

Brazilian Portuguese

1. Tu estás muito feliz hoje. (You are very happy today.)
2. Onde estás agora? (Where are you now?)
3. Tu estás com muita fome. (You are very hungry.)
4. Tu estás comendo uma maçã? (Are you eating an apple?)
5. Tu estás vendo o jogo na televisão? (Are you watching the game on television?)

Continental Portuguese

1. Tu estás a comer uma maçã. (You are eating an apple.)
2. Como estás? (How are you?)
3. Estás a estudar para o exame? (Are you studying for the exam?)
4. Tu estás com muito frio. (You are very cold.)
5. Tu estás a fazer o quê? (What are you doing?)