The question was asked about what the differences are between Human Factors and Ergonomics, so I emailed Professor Hedge at Cornell based on JSW's link and here is the answer he kindly provided:
In the rest of the world apart from the US, Ergonomics is the overarching discipline. Ergonomics (like medicine) is then organized into various sub-disciplines, two of which are physical ergonomics and cognitive ergonomics. Historically, in the US the term "Human Factors" was used for the discipline instead of "Ergonomics" (the modern version is a UK term) and originally Human Factors and Ergonomics were synonymous. The US professional society is the Human Factors and Ergonomics Society (with over 20 different specailization areas). Sometimes in the US a distinction is still drawn between "human factors", which is seen as focusing more on cognitive ergonomics, and "ergonomics" which is seen as focuseing more on physical ergonomics issues. In part this distinction is still maintained because of the fact that other disciplines (physical therapy, occupational therapy etc.) have begun to call themselves "ergonomists", but they can't be "human factors professionals" without appropriate degrees.
Hope this clarifies things.
Alan Hedge"
Interesting.