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

No.

While the fundamental meaning of "caixas" (containers, cash registers, or cashiers) remains the same, there are significant differences in typical usage and pronentaion.

In Brazil, "caixa" is the standard way to refer to an ATM (as part of the term caixa eletrônico), whereas in Portugal, the word multibanco is used almost exclusively. Additionally, while Brazilians frequently use "caixa" to refer to the person working at the register, Portuguese people more commonly use operador de caixa. There is also a slight difference in the vocabulary surrounding the word: Brazilians use papelão for cardboard, while Portuguese people use cartão. Finally, in terms of pronunciation, Brazilian Portuguese features more open vowels, while Continental Portuguese often reduces unstressed vowels, making the "a" in "caixas" sound much more closed or nearly silent.

Brazilian Portuguese Examples

1. As caixas de papelão estão no depósito. (The cardboard boxes are in the warehouse.)
2. As caixas do supermercado estavam muito lentas hoje. (The supermarket checkouts were very slow today.)
3. As caixas eletrônicas não estão funcionando. (The ATMs are not working.)
4. As caixas de som são muito potentes. (The speakers are very powerful.)
5. As caixas de presente são coloridas. (The gift boxes are colorful.)

Portuguese (Portugal) Examples

1. As caixas de cartão estão no armazém. (The cardboard boxes are in the warehouse.)
2. As caixas do supermercado estavam muito lentas hoje. (The supermarket checkouts were very slow today.)
3. Os multibancos não estão funcionando. (The ATMs are not working.)
4. As colunas de som são muito potentes. (The speakers are very powerful.)
5. As caixas de presente são coloridas. (The gift boxes are colorful.)