Question on Polygon network and DAPP’s relationship to main chain.

I noticed that the Polygon version of Aave doesn't appear to be the same as the mainnet version. There are less tokens to deposit/borrow, and none of my balances in mainnet appear in the Polygon chain.

My question is if DAPPs in a rollup exist in a separate space from mainnet. Are the liquidity pools in mainnet different from the liquidity pools in a rollup. I guess the best way to explain my question is if I deposit funds to a liquidity pool in a Rollup'd Uniswap, do I receive rewards from transactions against the mainnet Uniswap? Or would I only gain rewards from transactions in the Rollup?