Depending on the source, the jury is sometimes out on just what the difference is between a grandfather clock and a grandmother clock. For the most part, one is smaller than the other, but there is an overlapping range in there which makes some clocks either/or, depending on which criteria you use. I have read that a grandmother is a clock that is 6 feet, 3 inches tall or less. Others say that, she has to be a specific type of clock. And then there are grandaughters to further complicate things. What fun.