Title says.
It would be better it is presented as
1. POS : Pos is ....
2. POW: Pow is ...
3. What makes the difference is?
Thankyou.
1. POS : Pos is Proof of Stake. This is a reward for having your wallet synched with the network. This prevents it from 51% attacks (majority holder tries to bend the rules to change transactions). This is like interest from the bank and coins like MINT and Blackcoin use it.
2. POW: Pow is Proof of Work. This is the reward for mining coins (creating new coins with hashing power). This is the way Bitcoins are created. The hashing power is used to enable transactions between users in a decentralized way.
3. The difference?
See 1 and 2