The definition of “Vietnam vet” is debateable.
“Vietnam vet” served in Vietnam.
“Vietnam era” vet served during the war but not in the country.
Not exactly true... but almost... see my other post — service in Cambodia, Laos and Thailand (entering the war zone from those locations... entering in combat against the same enemy ...
VietNam vet is one who served in VietNam.
VietNam (era) vet is where the distinction varies and so does the stigma.
“Vietnam vet” served in Vietnam.
“Vietnam era” vet served during the war but not in the country.
Having spent some time in the Tonkin Gulf Yacht Club, I describe myself as a Vietnam vet. I'd add a further distinction on the "Vietnam vet" category, though - that of "Vietnam combat vet". I'd never represent myself as being a Vietnam combat vet. I reserve that term for the guys who were slogging through the muck and the mire while I was floating about and tossing in shells from offshore.