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

Yes

The word "publicar" is identical in meaning, spelling, and grammar in both Brazilian and European Portuguese. The only differences are in pronunciation and phonology. In Brazilian Portuguese, the vowels are generally more open, and the rhythm is more "syllable-timed," making the word sound more melodic. In European Portuguese, unstressed vowels are often reduced or "swallowed" (a "stress-timed" rhythm), making the pronunciation sound more closed or clipped. Additionally, while "publicar" is used for both books and social media in both dialects, Brazilians frequently use the anglicism "postar" for digital content, whereas Portuguese speakers are more likely to use "publicar" or "partilhar" (share).

Brazilian Portuguese Examples

1. Eu vou publicar uma foto no Instagram. (I am going to post a photo on Instagram.)
2. O cientista publicou os resultados da pesquisa. (The scientist published the research results.)
3. Eles publicaram um livro de poesias. (They published a book of poetry.)
4. Você já publicou o seu novo vídeo? (Have you already posted/published your new video?)
5. A empresa vai publicar um comunicado amanhã. (The company is going to publish a statement tomorrow.)

European Portuguese Examples

1. Vou publicar uma fotografia no Instagram. (I am going to publish/post a photograph on Instagram.)
2. O cientista publicou os resultados da investigação. (The scientist published the investigation results.)
3. Eles publicaram um livro de poesia. (They published a book of poetry.)
4. Já publicaste o teu novo vídeo? (Have you already published your new video?)
5. A empresa irá publicar um comunicado amanhã. (The company will publish a statement tomorrow.)