IKEA duvet questions and concerns? (:?

I have bought all my furniture at ikea, but I saw a (im uming duvet) on page 159 in the 2011 catalog ... if anyone could give me the name of it and tell me how they work... do you buy the duvet cover & a down comforter? Is it like a quilt? What is it and how does it work? I have that same bed (hemnes, full & the whole bedroom set) but I want to know what is the name of the cover that has a flowered pattern and I want to know how ikea divers work :) thanks!