Sunset and Twilight are basically the same thing, Starlight is not. Starlight is technically the same light source though usually is not used to refer to our sun but both Sunset and Twilight involve a time that occurs roughly the same time whilst Starlight does not.
 
Starlights name really doesn’t connect the same same way Sunset and Twilights does.

Applejack made me think of Hank Hill

@Bhazor  
She must be, since she’s apparently doing this before Twilight even got wings, so before those two had ever been introduced.

That apple is heavy.

She’s sharp like a tack is Pinkie.

Dashie is sleeping

Poor Spike.