I think lust is mostly based on being physically attracted to someone- you don't even have to know the person, or you could even know the person and not necessarily like their personality, but still want to have sex with them because of their physical attractiveness or even other reasons (like wanting your brother's wife simply because you hate your brother).
With love, you know the person really well, and are drawn not only to their physical attributes, but to their personality. You care about the person and what happens to them in their life, and you want not only physical intimacy with the person, but mental/emotional intimacy as well.