Why are human-factors engineering and ergonomics often used as names for the same field?

The terms human-factors engineering and ergonomics are considered synonymous because they both describe the application of scientific knowledge regarding human physical and psychological characteristics to the design of systems, devices, and environments for human use. While they may have minor differences in emphasis, both fields share the same fundamental goals: optimizing safety, comfort, and productivity in human-machine interactions.12

The variation in terminology is primarily geographic rather than functional. Human-factors engineering (often used interchangeably with human engineering) is the prevalent term in North America, whereas ergonomics—derived from the Greek words ergon (work) and nomos (law)—is the standard term used in Europe, Japan, and most other parts of the world.1

Within the broader scope of bioengineering, human-factors engineering is recognized as a specialized branch that integrates engineering, physiology, and psychology to refine the relationship between humans and machines. Other labels, such as biodynamics or manned-systems technology, are sometimes used by specialized groups, but these represent minor variations in focus rather than distinct fields.31