according to Cambridge dictionary: Pretty: (adjective) pleasant to look at, or (especially of girls or women or things connected with them) attractive or pleasant in a delicate way. examples: That's a pretty hat you're wearing. The sofa was covered in very pretty flowery material. She's got such a pretty daughter. Beauty: (noun) ---> Beautiful (adjective) the quality of being pleasing, especially to look at, or someone or something that gives great pleasure, especially by being looked at . examples: This is an area of outstanding natural beauty. The piece of music he played had a haunting beauty. beauty products/treatments

pretty is adjective, beauty is noun.... if there are other difference,hope somebody can point it out.