A perspective drawing is one that portrays an object as it appears to the eye from one point of view. The rails of a car-track, for instance, appear to converge. The parallel lines of any object appear to the eye to converge in like manner, and a perspective drawing will show this feature. Any picture or photograph furnishes an example of the perspective drawing.

The working drawing, on the other hand, is designed not to present a picture, as is the perspective drawing, but to indicate all the various parts of the object together with their dimensions. In other words, a working drawing is really three distinct drawings of the same object, each of which is drawn from a different point of view. A working drawing of a cube, for instance, would comprise three drawings exactly alike, because a cube presents the same appearance whether viewed from the front, top, or side. A working drawing of a book, on the other hand, would present drawings of three rectangles, each of which would have different dimensions.

This distinction between a perspective and a working drawing is an important one, but once made clear, is very simple. A perspective drawing is the result of what the eye sees, while a working drawing is the result of what the ruler and compass tell.