The main difference is that physical money exists as a liability on the balance sheet of the central bank. That is special however. Because - as you say - most

The main difference is that physical money exists as a liability on the balance sheet of the central bank. That is special however. Because - as you say - most of the money in existence is digital. However that digital money - ie. your deposit - exists as a liability of a private bank. Meaning if that bank goes bust you are only guaranteed to get back the amount that is insured (probably something like $100k in the US).