Stealth allows you to disguise as mobs also make objects like hats. Tombstone puts all of your items in a chest when you die.

 

Stealth: look like animals and monsters
Tombstone: puts items in chest upon death.

 

Tombstone does that provided you have access to the region.

 

Stealth makes you turn into a mob, tombstone occasionally protects your items. Tombstone really depends on how the plugin is feeling that day.