Twilight was the sight of the evening before sunset in the east and west horizon. Yes, that is how I interpret dusk, not so special and quite simple.
I know, dusk is so beautiful. Many people said, "at dusk, the sky turns orange". Even though it doesn't mean anything, only a beautiful painting in space. But there are many beautiful words engraved from the couplet, to describe the twilight or twilight of the twilight.
Yes, dusk can mean describing two things that are opposite, about beauty which means happiness, also about sadness when parting is likened to dusk.