At my FI we have two types of official checks. The cashier's check, where it's payable to someone else, and the teller's check, where it just shows the name of whoever's account it was drawn off of.

For both checks, the money is taken out of the account at the time of printing and the money is drawn off of some general ledger of our financial institution.

Reading up a bit on ye olde traveler's checks, it sounds like it was exactly the same as a teller's check. It was "as good as cash" (because it was drawn off of the account at the time of printing, so it couldn't bounce). It was an "official bank check", and it was made payable to the holder who would then travel to their destination and then go to a bank to get it cashed into local currency. LITERALLY a teller's check- a cashier's check made payable to the person who drew it off their account.

Was there something else that was "special" about a traveler's check that regular old teller's checks don't have?