• Skeleton spawn eggs spawn Wither Skeletons when spawned in the Nether
• Skeleton spawn eggs spawn Strays
• Horse spawn eggs spawn donkeys and mules
• Zombie spawn eggs spawn Husks

_{Original description:}

When they added the Wither Skeleton Spawn Egg in 16w20a, I thought the skeleton spawn egg would not spawn Wither Skeletons anymore. But instead, the Skeleton Spawn Egg still spawns Wither Skeletons 80% of the time in the Nether. This is also the case with Zombie/Husk and Skeleton/Stray.