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

No

In Brazil, "china" is used colloquially and as slang to refer to a boy, kid, or young man (particularly in certain regional or urban dialects). In Portugal, the word is used exclusively to refer to someone or something originating from the country of China; it is never used to refer to a child or young person.

Brazilian Portuguese

1. Aquele china é muito esperto. (That kid is very smart.)
2. Ei, china, vem cá agora! (Hey, kid, come here now!)
3. O china não quer fazer o dever. (The boy doesn't want to do his homework.)
4. Vi uns chinas brincando na rua. (I saw some kids playing in the street.)
5. Aquele china é muito legal. (That kid is very cool.)

European Portuguese

1. Aquele miúdo é muito esperto. (That kid is very smart.)
2. Ei, rapaz, vem cá agora! (Hey, boy, come here now!)
3. O miúdo não quer fazer o dever. (The kid doesn't want to do his homework.)
4. Vi uns miúdos a brincar na rua. (I saw some kids playing in the street.)
5. Aquele rapaz é muito porreiro. (That boy is very cool.)