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

No

The difference lies in typical usage and vocabulary. In Brazil, "marrom" (and its plural "marrons") is the standard, everyday word used to describe the color brown. In Portugal, while "marrom" might be understood due to the influence of Brazilian media, it is not the standard term. A Portuguese person would almost exclusively use the word "castanho" (and its plural "castanhos") to refer to the color brown.

Brazilian Portuguese Examples

1. Eu comprei sapatos marrons. (I bought brown shoes.)
2. As cortinas marrons combinam com o sofá. (The brown curtains match the sofa.)
3. Ele tem olhos marrons. (He has brown eyes.)
4. As caixas marrons estão no canto da sala. (The brown boxes are in the corner of the room.)
5. Ela gosta de usar tons marrons no inverno. (She likes to use brown tones in the winter.)

Continental Portuguese Examples

1. Eu comprei sapatos castanhos. (I bought brown shoes.)
2. As cortinas castanhas combinam com o sofá. (The brown curtains match the sofa.)
3. Ele tem olhos castanhos. (He has brown eyes.)
4. As caixas castanhas estão no canto da sala. (The brown boxes are in the corner of the room.)
5. Ela gosta de usar tons castanhos no inverno. (She likes to use brown tones in the winter.)