The main difference between the two is security.  In BTC/LN you have more freedom in how you choose to transact.  If you need to move a sizeable sum of wealth and security is paramount, it's best to do it on-chain.  If you need to make a small payment, where speed is a higher priority than security, you can transact off-chain.

SV takes a 'one-size-fits-all' approach and forces you to compromise.  There is only one way to transact and it's generally considered less secure than BTC's blockchain due to the vastly lower hashrate.