What Is the Primary Economic Difference between PoW and PoS Security Models?

PoW security is based on energy consumption and hardware cost; attackers must spend real-world resources (electricity and ASICs) to gain control. PoS security is based on capital lockup; attackers must acquire and stake a majority of the coin's value, which is then at risk of being slashed.

PoW security is external and continuous; PoS security is internal and relies on the protocol's ability to punish bad actors.