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

No

While the literal meaning of "caixinha" (a small box) is the same in both Brazilian and Continental Portuguese, there is a significant difference in typical usage. In Brazil, "caixinha" is frequently used idiomatically to refer to a tip (gratuity) or a shared fund of money collected among a group of people for a specific purpose. In Portugal, "caixinha" refers almost exclusively to the physical object; to express the idea of a tip or a collection of money, a Portuguese person would use different terminology.

Brazilian Portuguese Examples

1. Vou deixar uma caixinha para o garçom. (I'm going to leave a tip for the waiter.)
2. Fizemos uma caixinha para comprar o presente dela. (We collected some money to buy her gift.)
3. Guarde o seu anel dentro da caixinha. (Store your ring inside the little box.)
4. A caixinha de música parou de tocar. (The music box stopped playing.)
5. Esta caixinha é feita de madeira. (This little box is made of wood.)

Portuguese (Portugal) Examples

1. Vou deixar uma gorjeta para o empregado. (I'm going to leave a tip for the waiter.)
2. Fizemos uma contribuição para comprar o presente dela. (We made a contribution to buy her gift.)
3. Guarde o seu anel dentro da caixinha. (Store your ring inside the little box.)
4. A caixinha de música parou de tocar. (The music box stopped playing.)
5. Esta caixinha é feita de madeira. (This little box is made of wood.)