An autocompounder generally sells all farming rewards for a vault in order to buy more of the deposited token. The APY is generated by compounding the base rate, but the base rate for the yield is the same as that for the bulk deposit. Gains are realized continuously rather than at a time chosen by the farmer.
Concentrator can capture rewards from deposits in multiple different Convex vaults and merge them into CRV where they take advantage of the high CRV staking rate on Convex. Yields auto-compound at this higher rate, denominated in a top-tier DeFi token (CRV), and gains can be realized/claimed in CRV, CVX, or ETH at a time chosen by the farmer for maximum tax advantage.