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

No.

While the spelling of "guitarrista" is identical in both dialects, there is a significant difference in meaning and usage regarding the instrument being played. In Brazil, the word "guitarra" refers specifically to the electric guitar; therefore, a "guitarrista" is understood to be an electric guitarist. For the acoustic guitar, Brazilians use the word "violonista."

In Portugal, "guitarra" is a generic term that primarily refers to the acoustic, classical, or the traditional "guitarra portuguesa." Consequently, a "guitarrista" in Portugal is typically understood to be a classical or acoustic player. To refer to an electric player in Portugal, one must specify "guitarrista de guitarra elétrica."

Brazilian Portuguese (Focusing on the electric guitarist)

1. O guitarrista de rock é muito famoso. (The rock guitarist is very famous.)
2. Eu adoro o estilo desse guitarrista. (I love this guitarist's style.)
3. O guitarrista está afinando a guitarra. (The guitarist is tuning the electric guitar.)
4. Você conhece algum guitarrista de heavy metal? (Do you know any heavy metal guitarist?)
5. O solo do guitarrista foi o ponto alto do show. (The guitarist's solo was the highlight of the show.)

Continental Portuguese (Expressing the same idea of an electric guitarist)

1. O guitarrista de guitarra elétrica é muito famoso. (The electric guitarist is very famous.)
2. Eu adoro o estilo desse guitarrista de guitarra elétrica. (I love this electric guitarist's style.)
3. O guitarrista de guitarra elétrica está a afinar o instrumento. (The electric guitarist is tuning the instrument.)
4. Conheces algum guitarrista de guitarra elétrica? (Do you know any electric guitarist?)
5. O solo do guitarrista de guitarra elétrica foi o ponto alto do espetáculo. (The electric guitarist's solo was the highlight of the show.)