Creepers do not just come in the one skin of green. Theyre are other varieties.
Nether creeper Edit
Nether creepers are red, and their explosion can set everything inside that crater on fire. THey appear only in the Nether.
If you look at an endercreeper, it will instantly notice you, and start shaking. When you look away, they will TELEPORT TO YOU! They only exist in The End.
These creepers have tails and swim in the water.