Minecraft wiki entry for Parity_issue_list, associated text: Different AI.[more information needed]
Possess a charge attack.
Spawns four wither skeletons when at half health.
Will always break blocks that it touches.
Explode when created, half health, and killed (in Java, only explode when created).
Has a different spawning and death animation.
Has a health of 600 × 300 instead of 300 × 150.
Sometimes shoot wither skulls in a burst of four.
Doesn't regenerate health.