Forms of ILD

Idiopathic Interstitial Pneumonia (IIP) is a subgroup of Interstitial Lung Disease and a form of pulmonary fibrosis.
There are many different types of pulmonary fibrosis and IIP is just one form.  There are also many different types of IIP as listed above.  Idiopathic Pulmonary Fibrosis (IPF) is the most common form of IIP.