Accessories
A bow that is adorned to a character's skin, fur, hair for the purpose of improving a character's appearance.
Clothing
A bow that is attached to an article of clothing, or is perceived as part of an outfit.
Decorations
A bow that is attached to a prop such as a gift, or integrated with the background in some kind of creative way. Bondage
A bow that is associated with ribbon bondage. These probably shouldn't be treated as accessories.