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

No.

While the literal meaning of onda (a wave in the ocean or a physical wave such as sound or light) is identical in both Brazilian and Continental Portuguese, there is a significant difference in typical usage. In Brazil, "onda" is a very common slang term used to describe a "vibe," a "mood," a "situation," or a "trend." In Portugal, while the word is understood, speakers are much more likely to use words like vibe, ambiente, sintonia, or fase to express these same ideas.

Brazilian Portuguese usage:

1. Qual é a onda hoje? (What's the vibe today?)
2. Eu não estou na onda desse pessoal. (I'm not on the same wavelength as these people.)
3. A onda do mar estava muito forte. (The sea wave was very strong.)
4. Essa música é a minha onda. (This song is my vibe/thing.)
5. Ele está numa onda de muita preguiça. (He is in a wave/mood of much laziness.)

Continental Portuguese usage:

1. Qual é a vibe hoje? (What's the vibe today?)
2. Eu não estou em sintonia com este pessoal. (I am not in sync with these people.)
3. A onda do mar estava muito forte. (The sea wave was very strong.)
4. Esta música é o meu estilo. (This song is my style.)
5. Ele está numa fase de muita preguiça. (He is in a phase of much laziness.)