Grand Pianos: Unlike vertical pianos, grand pianos differ primarily in their length, and not in the type, size, or position of their actions (except that longer grands generally have longer keys than do shorter grands). Size classification of grands is less standardized than that of verticals, but a common breakdown is: Baby Grand (4' 6"–5' 6"), Medium Grand (5' 6"–6' 6"), Large Grand (6' 6"–7' 6"), and Concert Grand (over 7' 6"). Historically, many other names have also been applied to grand-piano sizes, such as Petite Grand, Parlor Grand, and Living-Room Grand, but these have no technical or standardized meaning.