Not Like Other Girls

On the surface, it's nice to hear someone say you're special. It's flattering to the ego to hear that you're better than the competition. That might be why this line is almost only found in young adult and teen stories. Writers may not expect teens to take subtext or larger social implications into consideration.

However it's meant, this line can be interpreted as a backhanded compliment. By saying that a your intelligence, sense of humor, or independence make you "different from other guys/girls," it's implied that the rest of your gender sucks (compare You Are a Credit to Your Race).

A more tactful person may ease the blow to feminism by saying she's different from other girls he knows or the kind of girls he usually dates. The inverse of this works as well.

Often said by the Ladykiller in Love. Compare and contrast I Can't Believe a Guy Like You Would Notice Me.

Examples of Not Like Other Girls include:

Anime and Manga

Kodachi meets Ranma for the first time in Ranma ½ and remarks, "You're no ordinary girl."

Film

Buffy the Vampire Slayer: At the high school dance, ~~James Dean~~ Luke Perry's character delivers this line to Buffy, she denies it.
Ella Enchanted

Prince Charmont: Ella of Frell, you're not like other girls.
Ella: You have no idea.

In Operation Petticoat, the chief, who doesn't like the idea of women on boats, finally gets to see the good side of the Chief Nurse and says, "You're not like other women. You're an engineer."

Literature

Peaceable in The Sherwood Ring proposes to Barbara (after she's tricked him into drinking sleeping drops) specifically because she's the only woman he's met who didn't act stupid in front of him. In Peaceable's defense, acting ditsy was the fashion among young women at the time. "I refuse to marry until I meet a woman as intelligent as I am--and not before." Point proven, Barbara.

Live-Action TV

October Road episode "How to Kiss Hello":

Eddie Latekka: You know what? You're not like the other girls I usually date. You're smart and funny and beautiful inside and out.

In the Star Trek: The Original Series pilot, "The Cage", Captain Pike says this about Number One.

Number One: She's replacing your former yeoman, sir.
Pike: She does a good job, all right. It's just that I can't get used to having a woman on the bridge. No offence, Lieutenant. You're different, of course.