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

No

The fundamental meanings of "se" (as a conditional conjunction, reflexive pronoun, or reciprocal pronoun) are identical in both dialects. However, the grammar (syntax) and typical usage differ significantly. In Brazil, there is a strong preference for proclisis (placing the pronoun before the verb), such as "Ele se viu". In Portugal, the standard is enclisis (placing the pronoun after the verb), such as "Ele viu-se". While the word itself is spelled the same, the rules governing its position in a sentence are a major point of divergence between the two varieties.

Brazilian Portuguese

1. Se você tiver tempo, me liga. (If you have time, call me.)
2. Ele se esqueceu de mim. (He forgot me.)
3. A gente se vê amanhã. (We'll see each other tomorrow.)
4. Não sei se ele vem hoje. (I don't know if he is coming today.)
5. O cachorro se assustou com o barulho. (The dog got scared with the noise.)

European Portuguese

1. Se tu tiveres tempo, liga-me. (If you have time, call me.)
2. Ele esqueceu-se de mim. (He forgot me.)
3. Vemo-nos amanhã. (We'll see each other tomorrow.)
4. Não sei se ele vem hoje. (I don't know if he is coming today.)
5. O cão assustou-se com o ruído. (The dog got scared with the noise.)