sea anchor, er drogue,
errrr what's the difference anyway?...
fundamentally, CaptRon has it right

it depends on what you need it for at the moment, and thats what it will be.
it was actually designed and built as a drogue/drift sock for smaller boats.
a sea anchor is big, and almost stops the boat in the water, in relation to the wind.... a drogue is much smaller and only slows the boat in the water, in relation to the wind.
either can be used for positioning the hull in the water in relation to the direction of the wind. some boats react better to this "attempted" positioning than others....
size and durability is the main difference....