This is one of those riddles where you can ask me questions. Like how a person was stabbed to death in the dead of winter and there's a puddle of water and you have to figure out how he died. (Spoiler: he stabbed himself with an icicle)

Little bit of background for anyone who doesn't know this yet. Ash is the reincarnation of Herobrine with the crimson tipped black wings and tail. So yes, there will be major character deaths at the end of S1. *shrugs*

Herobrine and Ash are standing in the same room. Ash has hidden his wings and tail in a way that makes his physical appearance identical to Herobrine. How does one tell the difference between the two?

No I'm not sure this is a possibility yet. Depends on whether or not I feel like having Ash reverse Herobrine's death.

But yes there is a way to tell the two apart.