Sea anchor
Modern commercial sea anchors are usually made of cloth, shaped like a parachute or cone, and rigged so that the wider end leads and the narrower end trails. When deployed, this type of sea anchor floats just under the surface, and the water moving past the sea anchor keeps it filled. Some varieties are cylindrical, with an adjustable opening in the rear that allows the amount of braking to be adjusted when deployed.
Anchor
So named due to its resemblance to a traditional agricultural plough. Many manufacturers produce a plough-style design, all based on or direct copies of the original CQR ("Secure"), a 1933 design patented in the UK (US patent in 1934) by mathematician Geoffrey Ingram Taylor. Ploughs are popular with cruising sailors and other private boaters. They are generally good in all bottoms, but not exceptional in any. The CQR design has a hinged shank. Despite the widely held belief that this is to allow the anchor to turn with direction changes rather than breaking out, the actual purpose is to prevent the weight of the shank from negatively impacting the fluke's orientation while setting. Other plough types have a rigid shank. Plough anchors are usually stowed in a roller at the bow.