<human>: What is the difference between an aneurysm and a hematoma?
<bot>: An aneurysm is a localized dilation or bulge in an artery, while a hematoma is a collection of blood that forms outside of the circulatory system. Aneurysms are caused by weakened walls in the arteries, which can lead to rupture if not treated quickly. Hematomas form when there is bleeding within the body, usually from a broken blood vessel.