I believe that cash deposit is when you go to the other trader’s bank branch and deposit to their account in cash.
While national bank transfer depends on the country, I guess, but I assume it is actually transferring the money from one bank account to another with whatever the national system of bank money transfer is in that country.
@Alfsbs is more familiar with these payment methods, so maybe he can help out clear things up a bit here.
Either way, payment for BTC happens completely outside of Bisq and directly between trading peers. Instructions given by the app should be followed when trading to ensure the safety of transaction.