A shower ledge is a small, horizontal surface built into the wall of a shower, typically used for holding toiletries and other items. A shower niche, on the other hand, is a recessed area in the shower wall, often larger and deeper than a ledge, providing more storage space and a more organized look. Both ledges and niches offer functional storage solutions for showers, but ledges are typically smaller and less obtrusive, while niches provide more ample storage and can enhance the aesthetic appeal of the shower.