Unlike general illustrations, technical illustrations use strict conventions to show information. One of the main characteristics of technical illustration is the use of specific projections to display subject matter – for example, orthographic, oblique and isometric projections; different types of vanishing-point perspective projections; and exploded-view projections.  

Technical illustrations are used to show architectural, engineering and manufacturing information to specific audiences. They also communicate complex subject matter to a nontechnical audience, such as illustrating product information or explaining a mechanical procedure.

Source: Department of Environment and Energy (2017). YourHome: Australia’s guide to environmentally sustainable homes, 5th edn, Department of Environment and Energy, Canberra.