A photojournalist is simply someone who tells stories using photography rather than words.
Most people's idea of a photojournalist is that of a war photographer, running around in a flak jacket or one of those big fishing vests with bulging pockets and half a dozen cameras hanging off them. Or a member of the paparazzi scrum outside a nightclub with a flash going off at 6 frames a second. Both of these stereotypes may be a practising a type of photojournalism, but that doesn't mean all photojournalists conform to the stereotype.
I'm a photojournalist. When I'm working at a wedding I wear a suit. I carry two cameras and a small shoulder bag. Otherwise I try as much as possible to blend in and look like a guest. I'm not a war photographer or a paparazzi and I see no reason to act like one.