Isometric projection is a single 2D representation of a 3D object in which the 3 orthogonal axes are shown as lines intersecting at a point (an arbitrary origin) and at 120° to one another. The axial lines are subdivided into unit measurements
Orthogonal projection requires three separate 2D views of the same object: top view and two side views. These are separate scale drawings of the object as viewed along each of the three orthogonal axes. The two axes are subdivided into unit measurements.