Beyond a certain size a window unit stops being available and starts being a special order with a long lead time. Storefront has no such ceiling: it is assembled to the dimension.
A double height entry or a great room wall is a grid of fixed lites with horizontal rails at the floor line. That grid is a storefront.
A glass entry door hung in the same framing as the wall around it, so the sightlines run straight through instead of stepping.
The tall narrow window wall beside a staircase, usually with a rail at each landing. Pairs naturally with a glass railing.
Outbuildings where you want glass on three sides and the structure has to come from the framing itself.
Older houses move. Storefront is cut to what the opening actually is, which is a real advantage over a rectangular unit.