I know Bitcoin is running on a proof of work consensus algorithm. Recently I discovered proof of stake by reading up a bit on Cardano and Ethereum's 2.0 plans.

What is the difference between these two, how does POS reduce the energy required to mine a block transaction and are either of these more secure than the other? Basically what are the pros and cons of each.

Also if POS consumes less energy, then wouldn't it be a good idea for Bitcoin to transition to a POS algorithm?