What is the difference between molding and trim?

While the terms molding and trim are frequently used interchangeably in conversation and construction, there is a subtle structural distinction between the two concepts. Trim is a broad, overarching umbrella term that encompasses all wood, MDF, PVC, or synthetic materials used to finish, border, and cap off raw edges in a building, which includes functional, flat boards like plain door jambs, window sills, and basic baseboards alongside decorative elements. Molding, on the other hand, is a specific subcategory of trim that is specifically characterized by its distinct, ornamental profile—such as the curved contours of crown molding, decorative casing, chair rails, or picture rails—designed primarily to add architectural detail, depth, and elegance to a room. Therefore, while all molding is technically a form of trim, not all trim possesses the ornate profile that defines traditional molding.