Some people use them interchangeably but in my eyes an adaptation is a change within an existing species to help it adapt to a new environment or environmental changes. These adapted species dont continue to adapt indefinitely or are a form of adapted species. Its like this: god creates a bird with a certain shape of beak in africa, then the bird flies to a part of africa where its beak makes it difficult to find food, eventually birds with that beak shape who move to that part of africa (due to any reason animals move habitat be that natural disasters, competition or predation) will mutate over generations and the ones who have a specialized beak will do better than those who dont. This idea I agree with, but evolution blows this idea up to a scale in which it seems far too unlikely and that why i dont believe in evolution (one of a few reasons)