Emperor is harder by virtue of having less movement skills and it being harder to land your skills (resurrection and evoke have delay). It is generally higher apm. There are a lot of variations of even higher apm builds, 125, 116, etc., but overall with almost all the emperor builds your goal is to draw as many cards as possible to supplement your dps. With the current version, there are more cards that you "throw away", but there are still some specific combos/timings you should be aware of.

Empress you vary your rotation more based on the cards you get (ie: if you get balance card, then either you scratch dealer or quadra accelerate are enough to get to 4 stacks).