i guess the difference is that like, i don't think the people of ireland are being significantly harmed by americans pretending to be 1/16 irish and getting soused on guinness once a year, whereas native american artists can really be harmed by people buying fake native items instead of legitimate ones. but if some famous fashion designer took some, i don't know, wool sweater patterns made by impoverished galway grannies or whatever, and starting selling them as exotic celtic designs without crediting or paying the original artists, that would be bad.