Jimmy -- I always called them that too until I went through an old government weed publication that identifies the Scottish thistle as being smaller and easier to kill (go figure ). Either way they are both considered a noxious weed in Ontario and legally you are obligated to remove them in agricultural areas according to the noxious weeds act of Ontario (still on the books). (I have one area that I leave them in for the hummingbirds -- guess I better watch out for the weed police.)We call them Scotch thistles up here. As the rest of the guys say, they're easy to kill. NOTE: A lot of birds love the seeds, finches in particular.