When you borrow from another culture, but you maintain a hatred for or a disdain of that culture, that's appropriation. And when you literally try to revise history or pretend that you actually invented the things that you got from another culture, that's wrong.
Black Americans invented every major form of music in the US. But you wouldn't know this because it's been whitewashed. Many of the hit songs from the 1950's and 60's were white artists, stealing the work of black artists, and doing a worse job with the music! Elvis stole black dance moves and music, performed them for white America, and never credited the source, for instance.
And it's not just limited to music and dance. Fashion, slang, even food, all stolen from us. But a lot of times it's warped to fit the mainstream. Full lips and big butts are desirable in white women. Black women with these traits are still shown as less attractive. Tanned skin, another example, or certain hairstyles.
You can have cultural cross pollination in a respectful way. That's not what we have here in America, not between black culture and white culture, at least.