Niches – These are shallow recesses or hollow spaces in a wall, often shaped like an arch. They are usually used to place statues, candles, or religious images. Example: a small hollow in a church wall where a saint’s statue is placed.Grottoes – These are small caves or artificial cave-like structures, often used as shrines. They are bigger than niches and can be natural or man-made, usually decorated with stones, plants, or religious icons (like the grotto of the Virgin Mary).A niche is a small hollow in a wall, while a grotto is a cave-like structure, often outdoors.