I don't really deserve a Pulitzer, but thanks! :) Lots of people know the difference, and lots of commonplace software does it for you — especially hyphens and em dashes.

There was a thread on HN in the last few months. Here's a quick, general guide:

* Hyphens join things into one term: sun-bleached

* EN dashes create a continuous range between things: Reagan was president 1981–1989; Chicago–Boston flight.

* EM dashes create a break between things: What the—?; I was walking — my car was out of gas — when I saw the accident.