Quicker. Milder. Both are caused by the legionella germ. Pontiac favor happens quicker. It's milder and doesn't have breathing problems like cough chest pain, pneumonia. Good question!
It is a milder form. Pontiac fever is a milder form of legionnaires' diease, both illnesses caused by the bacterium legionella pneumophila the incubation period is short, from a few hours to 2 days, before the onset of fever and muscle aches. Persons with pontiac fever do not have pneumonia. They generally recover in 2 to 5 days without treatment.