> Taken to its conclusion, PoW and PoS are exactly the same.

> In a PoW environment you can take some of your coins, 'stake' them by buying a share in a mining pool [...]

Playing devil's advocate: there's a small but important difference in that, for PoW, you can "stake" coins from outside the system (for instance, by buying an ASIC miner with real money), while for PoS, the coins you "stake" must come from within the system itself. That is, PoS is a closed system.