I've had great feedback about my previous post and one of the most interesting questions was , "What is the difference between a documentary photographer and a photojournalist?"
Documentary photographers tend to stick with a particular subject for a length of time doing nothing else. Their focus and attention is narrower than a typical photojournalist.
The photojournalist tells stories wherever he finds them and probably goes into an area for a few hours, a week, maybe a month and then moves on to the next story. The photojournalist is concerned with bringing the story to a wide public audience, their readers, while a documentary photographer wants to record something for prosperity or sometimes a specific audience.
Documentary photographers usually take images for publication, but sometimes only for an exhibition in an art gallery or other public forum. Sometimes an organisation or company will commission documentary photography of its activities, but the pictures will only be for its private archives.
In many ways the documentary photography and photojournalism overlap and the distinction is blurred. It's probably most useful however to regard documentary photography as a subcategory of photojournalism.