Castaño vs Moreno vs Marrón
 

What are the differences between the uses of "castaño, moreno, and marrón" in terms of hair and eye colour?

Many thanks.

None between "castaño" and "marrón" when talking about hair (in Mexico it's only "castaño").
I have only heard "ojos marrón" or "ojos cafés" (most common in Mexico).
"Moreno" is mostly used about skin. You don't say "tiene el cabello moreno", but you may well hear "es una persona morena". In that case, they would probably have to explain if they're talking about a person with dark hair or with dark skin.

Thank you again!

ojos claros (azules, verdes, otoñales, grises)
ojos marrones
ojos negros

cabello cano (platinado, when artificially obtained)
cabello claro (rubio, rojizo, castaño claro)
cabello castaño
cabello negro

For me, "ojos café" is dark brown.