While the terms are often used interchangeably, there's a key difference:
* Fur: Is typically found on animals like cats, rabbits, and bears. It consists of two distinct layers: a dense, soft undercoat for insulation, and longer, coarser guard hairs for protection.
* Hair: Is generally found on mammals like dogs, humans, and horses. It has a single layer and can be short or long, thick or fine, depending on the breed or species.
So, even though we might say "dog fur," they technically have hair.