marron ou brun?

No, they are not the same in use, or in ‘meaning’’

Addressed previously in QandA under linked topic here:

Colour descriptions change according to gender and number (French Colour Adjectives)

See also this external link for discussion:

http://www.aussieinfrance.com/2016/11/fridays-french-chataigne-chestnut-marron-brun-brown/

marron means chestnut and implies brown with a hint of red and is typically used when describing eye color. For hair color brun or châtain is often used instead of marron. Brun is a more commonly used way to say brown for lots of things.