Agaric and Oyster fungus

Agaric noun - A saprophytic fungus of the order Agaricales having an umbrellalike cap with gills on the underside.

Oyster fungus and agaric are semantically related. In some cases you can replace phrase "Oyster fungus" with "Agaric", this terms are similar.

Oyster fungus noun - Edible agaric with a soft greyish cap growing in shelving masses on dead wood.

Agaric and oyster fungus are semantically related. You can use "Agaric" instead a noun phrase "Oyster fungus".