Compresses are soaked external dressings, hot or cold: A piece of cloth (traditionally linen or muslin) is allowed to soak in an infusion or decoction, to be applied to the affected area and held in place with bandages.
Poultices are hot external applications of a prepared paste or pulp. The boiled fresh parts of a plant or a paste mix of hot water and powder/spice/ground part of a healing plant, is applied direct to the skin/affected area. Utilized to draw out impurities; abscesses, pus, stings, splinters etc.. The crushed parts of a plant can be applied cold as a poultice too.