Monroe was sexy in a somewhat over the top way, but she never seemed to quite make it to the “Whee, I’m a total whore!” kind of way.
Paris, on the other hand, seems to believe that more equals…a need for extra. Extra trash, extra breathy syllables, extra affectation, extra extra ditziness. The latter, I am not entirely convinced that she fakes.

Monroe was prettier.
Paris is pretty in a “Sure, why not, I’m drunk” kind of way.

Monroe could dress herself.
Paris…Paris by choice can’t wear anything that doesn’t look like it belongs in a Star Wars cantina.

Monroe at least had the decency to wear underwear in public.
Paris doesn’t seem to grasp the idea that underwear isn’t worn for the sole purpose of showing it to people.

Monroe had a grasp of the concept of class.
Paris…well, you’ve seen her.