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

Yes

The word "alto" has the same meaning, spelling, and grammatical function in both Brazilian and Continental Portuguese. It can be used as an adjective to describe height (tall/high), volume (loud), or status (high/exalted), or as a noun to refer to a summit or peak. The only difference is in pronunciation. In Brazilian Portuguese, the pronunciation is generally more "open," with clearly articulated vowels and a more syllable-timed rhythm. In Continental Portuguese, there is significant vowel reduction, meaning unstressed vowels (like the 'o' in the middle of words or the 'a' in 'alto' if followed by certain sounds) are often swallowed or pronounced very subtly, resulting in a more stress-timed rhythm.

Brazilian Portuguese Examples

1. Ele é um homem muito alto. (He is a very tall man.)
2. Por favor, não fale tão alto. (Please, don't speak so loud.)
3. O preço da gasolina está muito alto. (The price of gasoline is very high.)
4. O som da música estava muito alto. (The music volume was very loud.)
5. Ela mora em um prédio muito alto. (She lives in a very tall building.)

Continental Portuguese Examples

1. Ele é um homem muito alto. (He is a very tall man.)
2. Por favor, não fales tão alto. (Please, don't speak so loud.)
3. O preço da gasolina está muito alto. (The price of gasoline is very high.)
4. O som da música estava muito alto. (The music volume was very loud.)
5. Ela mora num prédio muito alto. (She lives in a very tall building.)