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

Yes

The meaning, spelling, and grammar of "até" are identical in both Brazilian and Continental Portuguese. The only differences lie in pronunciation and how the word interacts with the surrounding sentence structure. In Brazilian Portuguese, the vowels are generally more open and clearly articulated. In Continental Portuguese, vowels (especially unstressed ones) tend to be more closed or "reduced," which can make the word sound slightly shorter or more clipped.

Brazilian Portuguese Examples

1. Até amanhã! (See you tomorrow!)
2. Eu trabalho até tarde todos os dias. (I work until late every day.)
3. Até mesmo as crianças entendem isso. (Even the children understand that.)
4. Vou ficar aqui até as seis da tarde. (I will stay here until six in the afternoon.)
5. Até que enfim você chegou! (At last you arrived!)

Continental Portuguese Examples

1. Até amanhã! (See you tomorrow!)
2. Eu trabalho até tarde todos os dias. (I work until late every day.)
3. Até mesmo as crianças percebem isso. (Even the children understand that. Note: 'Perceber' is more commonly used than 'entender' in Portugal for this context.)
4. Vou ficar aqui até às seis da tarde. (I will stay here until six in the afternoon. Note: Portuguese people almost always include the article 'as' after 'até' when referring to specific times.)
5. Até que enfim chegaste! (At last you arrived! Note: Uses the 'tu' conjugation, which is the natural way to address someone informally in Portugal.)