I see it as something finer than a hunter, has to be a bit flashy or special, well turned out, perfectly turned out, no blemishes or obvious faults. Good manners. https://en.wikipedia.org/wiki/Show_hack
http://www.theshowring.info/Hacks.htm The lightest, flashiest show horses under 16hh(?) Lighter than riding horses as well as obviously hunters. I don't think they gallop, but they do rein back, and in championships are often ridden one handed. Ladies in Navy, men in tweed. In championships men in tailcoat suits.