For entering the USA, foreign flight crew visa categories include:
C-1D Combined transit and crewmember visa
D-1 Crewmember departing on same vessel of arrival
D-2 Crewman departing by means other than the vessel of arrival
Temporary visitors for pleasure to the US are granted B-2 visas.
I wouldn't be surprised to find that nations that require visas of US citizens have similar visa categories.