“Shadow drive is a second layer on top of the Solana Chain - as apposed to its own standalone chain”.
Shadow Drive IPFS - Solana based IPFS (permission less cloud for storing data) powered by the Solana blockchain. Shadow Drive is a second layer protocol that has it's own proof of stake.
Ledger (blockchains are ledgers) - record history of how things have changed over time & all of those changes combined give you the current “state”. Solana is about “Accounts” & the “State” of those accounts