Upholder :: Upholder (n.) One who, or that which, upholds; a supporter; a defender; a sustainer..
Upholster :: Upholster (v. t.) To furnish (rooms, carriages, bedsteads, chairs, etc.) with hangings, coverings, cushions, etc.; to adorn with furnishings in cloth, velvet, silk, etc.; as, to upholster a couch; to upholster a room with curtains..