Safe deposit box: an asset of the bank in case of liquidation, the contents is not yours when you'd most need it.
Insured: Also a counterparty risk: solvability of the insurance company.
At least here where I live (Germany) deposit content is not an asset of the bank (“Sondervermögen”). It cannot be used for liquidation if things go south for the bank. I assume this is true for most parts of the globe.