Some dig into the seabed, some silt in, and others are heavy enough to simply sit on the seabed. Some anchors hold extremely well in sand or mud, others fare better in shale or rocky bottoms.
Some anchors never touch the seabed while others are permanently embedded.
Anchor selection should be based on the size and type of your boat and the condition of the bottom where you do most of your boating. A lunch hook is an exceptionally light anchor that is set for short daytime stops when crew stays aboard. The working anchor is used for standard overnight anchoring. I feel cruising boats should carry two working anchors, one for hard bottoms and one for soft bottoms. A storm anchor is used in heavy weather and can be of any type, as long as it is very heavy.