A sea anchor is a parachute type affair that really puts the brakes on a boat. It would be set on a long line and bridle from the bow of a cat or tri. sometimes and un-even bridle is best as the boat will lie diagonally to the waves. The sails would be down if a sea anchor is deployed. The foils would also be raised - keels/skegs on a multi are a bad idea at this point

A drogue is similar to a parachute sea anchor, but is designed to be towed at a speed [Less drag] off of the stern of a cat or tri that is running away from the wind direction. It is supposed to give the boat more stability and directional control.

In the recent Round Britain Race, the multihulls all picked up pairs of car tyres in Lerwick to be used on the howlin' downwind leg that was ahead of them [As drogues].