-Withers seem to not drop coal
-Blazes shoot even when player is not on sight (or sound bug)
-Chances of mobs spawning with gear is significantly higher from what I've seen. I got a Flame bow from a skeleton! ((Not sure if this is a bug)
Mobs do not attack immediately when player is seen.
Not sure if you're taking about the Wither or Wither Skeletons on the first one.
Dupe of MC-47699