That's really the reason I posted my own definitions cause I do make this distinction and I think most people dont.
Everything else being equal, would it mean the same thing to you in both instances if in one case a girl asked you to "have sex with her" and in another she asked you to "fuck her". Same tone of voice, same facial expressions, no other differences apart from the word choice. Is your interpretation of what she wants to do with you exactly the same in both instances or different?