<font color="blue"> Which term is the correct one??? </font>
It depends on the context...I think. /forums/images/graemlins/smile.gif
Bush Hog is a brand name, whereas brush hog is a generic term for a mower that's not a finish mower, i.e., a rotary cutter. In Australia, and maybe other countries, they're called slashers. Although, as you noticed, people use Bush Hog and brush hog interchangeably.