Wrapped Luna (WLUNA) is an Ethereum token designed to represent Terra (LUNA) on the Ethereum blockchain. It is not LUNA, but a separate ERC-20 token designed to track the value of LUNA.
WLUNA is designed to allow LUNA holders to trade, hold and participate in decentralized finance ("DeFi") applications on Ethereum. Through WLUNA partners, 1 LUNA can be exchanged for 1 WLUNA and vice versa.

Terra is an algorithmic stablecoin platform that runs on the Proof of Stake (PoS) built with Tendermint, which is the bottom layer of the Proof of Stake blockchain.
LUNA is Terra's platform token, which is used for the issuance of stable coins (TerraSDRs), price stabilization mechanism, and network governance.
Users can exchange LUNA tokens for TerraSDRs stablecoins and vice versa. The price stability of such stablecoins is guaranteed.