kigmatzomat
Legend
The designers have stated somewhere like in a blog post or a tweet, that Feywild is a border plane to the Positive Energy Plane and that Shadowfell is the border plane to the Negative Energy Plane.
But nothing written in any of the books has ever stated that though.
5e moved the Positive/Negative farther away to outer-outer planes and sometimes refers to them as Positive Energy and Negative Energy planes. Which is actually more apt, imo, given they are sometimes described as lacking a proper terrain...or terra. So as "material" planes, the feywild seems more "positive" and shadowfell is clearly more "negative"
I see a clear difference from the Raven queen and the Gloaming Queen. The first is more rot and decay while the latter is enjoyjng malicious destruction, where even the animals are murder hobos.