Hello @sapwood I express my gratitude as your student and appreciate your educative lectures,below is my homework task.

WHAT IS THE DIFFERENCE BETWEEN PoW AND PoS

what is the meaning of the letter PoW

PoW means proof-of-work.

General work which requires a lot of computing effort to solve the complex mathematical puzzle.

source

On PoW the miner's must validate the transaction, keep proper record of all transaction on the public ledger, which becomes part of the "chain of block".

With PoW all transaction need to be verified and validated, because immediately any transaction is carried out it goes into the unconfirmed pool,then the miners will see to it that the cryptographic puzzle is verified and it will be added to the block with a timestamp and it previous timestamp,no second on the same transaction because it won't be valid.

More to that in PoW miners are selected randomly to ensure better degree of decentralization.

Advantage of PoW.

PoW is secured and ensures higher degree of decentralization.

Disadvantage of PoW.

PoW is energy and time consuming.

This is totally different from PoS(proof of stake)

Because on PoS the higher the stake the higher the chance to become a validator in minting a block.

There is nothing like mining rig.

PoS helps the price dynamic of the tokens to remain locked at a certain percentage.

Advantage of PoS.

It saves energy because it doesn't require high computing work.

It attract many stake holders to earn better rewards.

Disadvantage of PoS

The transactions are no secure,there is no record of proof of work over the transactions.

PoS is centralized.

With all this I believe the PoS is better in scaling capicity tho is less secured no wonder some cryptocurrency like DASH,NEO,TEZOS,and ETHEREUM has already made an announcement of switching over to PoS from PoW.

Thank you @sapwood