Not really the same. Mining pools simply point their capital at an api while those staking with exchanges literally give them their capital. With stratum V2 on the horizon (allows miners to construct their own blocks while in a pool) the similarities will be even less.
But either way, it's a central entity ordering transactions and putting transactions in blocks.
The real question is, how much capital do you need to be a block producer. For Ethereum that's 32 ETH; with 400K validators and 12-second blocks you'll produce one every 55 days on average.
So on Bitcoin, the largest remaining PoW network, how much capital do you need to produce a block that often?
Let's see....actually 14M ETH staked now so about 430K validators. Blocks are 12 seconds, so blocks per day is 24 * 60 * 5 = 7200. Taking 430,000/7200 gives 60 days.
But they're saying returns are more like 6%. Where are you getting return per block? (Also I think some of the return comes from doing block attestations, on every block.)