What is the difference between a backfire, headfire, and flank fire?

A backfire is a fire that burns into the prevailing wind, it is typically slow moving with shorter flame heights and lower fire intensity. Headfires are fires that burn with the prevailing wind; they are the fastest moving fire type, with the longest flames and greatest intensity. Flank fires are fires that burn or spread parallel to the prevailing wind direction; their behavior is between that of a backfire and headfire.