Chamfer and Bevel
A chamfer as a beveled edge of a hole, frequently cut at a 45° incline to the 'normal' surface to breaks a sharp edge. It is also used when performing a deburring operation; running a small cutting tool around the perimeter of a hole (especially in metalworking) to remove any sharp edges or splinters. In this case, the chamfer is non-functional, it is just a result of the deburring operation. Generally the most common form of chamfer is with 45º.
Compare to chamfer made at a 45° angle to the adjacent principal faces, whereas bevel is a sloping edge between two principle faces. A bevel is nothing more then an angled face. It reduces a square edge on an object to a sloping edge, like a chamfer, but encompasses the entire edge. So it looks like an angled edge, rather then a broken corner.