The difference between these types of views lies in the fact that in the Perspective view we can see that the objects have different sizes depending on the distances they are from each other; is other words; In the Orthogonal or Orthographic view we cannot notice the difference in size regardless of the distance between the objects, as we can see in the following images:

Viewing objects in a scene with the Perspective view in Blender.

Viewing objects in a scene with the Orthographic or Orthogonal view in Blender.