Pneumonitis refers to lung tissue inflammation. Bisegmental pneumonitis refers to inflammation of the lung tissue with occurs in two segments.

Pneumonia involves the swelling or inflammation lung tissue and it is infectious whereas pneumonitis is not infectious.

Hypersensitivity pneumonitis refers to an inflammation of the lungs caused by repeated breathing in of a foreign substance, such an organic dust, a fungus, or a mold.

No. Pneumonitis means inflammation of the lungs (e.g. from a chemical or a toxin), whereas pneumonia means infection of the lungs (which could be communicable).

yes