Are colors interchangeable?
Red is 빨간색 or 홍색. Green is 초록색 or 녹색. Blue is 파란색 or 청색. In each case, the first version is "pure Korean" while the second version comes from Chinese. Probably there are many other examples. Is there a difference in usage, either in terms the actual color referred to or when one or the other is more appropriate?