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

No.

While the fundamental definition of "juntar" (to join, to gather, to collect) remains the same in both dialects, there are significant differences in typical usage and pronunciation.

Usage: In Brazil, "juntar" is the most common colloquial way to express saving money ("juntar dinheiro"), whereas in Portugal, the verb "poupar" is the standard. Additionally, when referring to gathering people or objects, Brazilians frequently use "juntar," while Portuguese people often prefer "reunir" (for people) or "unir/montar" (for parts/objects). In mathematical contexts, Brazilians use "juntar" to mean "to add," while a Portuguese person would typically use "somar."

Pronunciation: Brazilian Portuguese is characterized by more open, musical vowels and a more rhythmic cadence. Continental Portuguese features much more reduced, closed, or even deleted vowels, making the speech sound more "consonantal" and staccato to many listeners.

Brazilian Portuguese Usage

1. Vou juntar dinheiro para viajar. (I am going to save money to travel.)
2. Vamos juntar o pessoal no domingo. (Let's get everyone together on Sunday.)
3. Ele juntou as duas peças do brinquedo. (He joined the two parts of the toy.)
4. Junte dois mais dois para saber o total. (Add two plus two to know the total.)
5. Junte suas coisas na mala rapidamente. (Put your things together in the suitcase quickly.)

Continental Portuguese Usage

1. Estou a poupar dinheiro para viajar. (I am saving money to travel.)
2. Vamos reunir o pessoal no domingo. (Let's gather everyone on Sunday.)
3. Ele uniu as duas peças do brinquedo. (He joined the two parts of the toy.)
4. Some dois mais dois para saber o total. (Add two plus two to know the total.)
5. Arrume as suas coisas na mala rapidamente. (Pack your things in the suitcase quickly.)