User blog comment:Thedoucheinthenorth/The Civil War - Why it is great/@comment-4692902-20121102005428/@comment-3492791-20121107044221

Reachmen are Bretons who were the native population of The Reach before Tiber Septim conquered it for the Nords. The descendents of the native Bretons are called Reachman.

The local Nords of the Reach treat the Reachmen very poorly, treating them like second class citizens and forbidding the practices of their religion. Thus some of the Reachmen decided that they didn't care for the Nords, and vowed to kill them all and retake the Reach, which they believe is rightfully theirs. The group they formed became known as the Forsworn. Do to the goals of the Forsworn, their members consist of almost entirely Reachmen...except for Borkul the Beast for whatever odd reason. However not all Reachmen share the ideology of the Forsworn.

Saying that Reachmen and Forsworn mean the same thing is like saying that, because the NAZI political party was comprised mostly of Germans, the word German and Nazi are intergangable terms.