Interesting point. So you're saying that "girls" is not really being used as a noun phrase, but rather as an abbreviated clause. Thus we use the conjunction "t

Interesting point. So you're saying that "girls" is not really being used as a noun phrase, but rather as an abbreviated clause. Thus we use the conjunction "than", while we would use the preposition "from" with a real honest-to-goodness noun phrase. "Than" is a preposition, too, but only when referencing a comparative. So, "A cow has more than one stomach." But, "Cows are different from people." OTOH, I guess you would prefer, "Cows eat different food than people," (?) since "people" in that sentence is really short for "people eat". I'll have to ponder this. Thanks for a thought-provoking comment. EDIT. And perhaps the source of all the actually poor uses of "different than", is that many people mentally classify "different" as a comparative.