for the most part, the Empress looks and acts like an ordinary xenomorph queen. however, there are two things that set her apart from other queens: her white carapace and the fact she carries a massive, hand-held GAU-8 avenger. yep, that's all there is to say on the matter.
role in the hive
the Empress mainly just sits around churning out ovomorphs like most queens do. she lacks a telepathic link to her spawn, unlike most queens, and instead relies on the Pale King to issue commands. however, it is possible that the Pale King is ruling the skaedrell according to his own whims, instead of the empress's.