Plum duff and Plum pudding

Plum duff noun - A stiff flour pudding steamed or boiled usually and containing e.g. currants and raisins and citron.

Plum pudding and plum duff are semantically related. In some cases you can use "Plum pudding" instead a noun phrase "Plum duff".

Plum pudding noun - A rich steamed or boiled pudding that resembles cake.

Plum duff and plum pudding are semantically related. Sometimes you can replace phrase "Plum duff" with "Plum pudding", this phrases are similar.