In Perspective Camera mode, part or assembly models display in three-point perspective, a visual effect in which parallel lines converge on a vanishing point. This effect is the way real objects are perceived by the human eye or by a camera.
Use Perspective Camera mode to provide a sense of how parts and assemblies would appear to the human eye when manufactured. You can also use Perspective Camera mode to ascertain the relative position of same-size objects in an assembly without having to rotate the assembly.