Pow (proof of work) is when anyone can go to the platform start mining and collect the mining reward from mining blocks like bitcoin. In POS (proof of stake) the stakeholders control the mining and collect all the mining fees so not just anyone can go into it and start mining you need to control a large amount of coin for it to be worth trying to mine. POS there is less inflation but to mine you have to control a lot of the currency so it is almost like centralization you have to own a lot of coin. There is less inflation cause all the mining fees go to the stake holders so they don't really need new miners.