Good question, mate! Simplified Payment Verification (SPV) at Lightning Network are both solutions to Bitcoin's scalability issue, but they function in different ways.

SPV is a method that allows a user to verify if a transaction is included in the blockchain without downloading the whole blockchain. It's lightweight and great for mobile devices.

On the other hand, Lightning Network is a "second layer" solution that creates off-chain payment channels. Instead of recording every single transaction on the blockchain, it allows users to transact multiple times off-chain and then record the final balance on-chain.

So SPV deals with verifying transactions while keeping data storage low; Lightning Network focuses on enabling faster and more efficient transactions by reducing load on main chain.