At our house, everything that you hang from "the little hooks" are ornaments. However, we would probably include all the glass or pseudo-glass ornaments that are non-representational in the sub-class of ornaments called balls, i.e. any shape as long as it's not meant to be a bird or a snowman or an icicle or ... The balls go on before the rest of the ornaments because the balls are just pretty while the "rest" are meaningful or special - stuff the kids made, commemoratives, etc.