These two trolls are meant to be ambient mob, which means that they are adapted to the difficulty of Minecraft.
The green troll is a cave one. It likes dark places but also nearby forest in which he gathers sheeps, rabbits and cow to prepare his meal. He eats a lot and is kinda grumpy. You may not want to bother him for sure !
The demoniac troll is coming right from the Nether. He is a protector of dungeons as well as a guardian for the souls that lives in the Nether. He can be brutal and merciless with his sharpened battleaxe. You may fear him, as he’s strong and determined to kill you.