How are an atheroma, atherosclerosis and ischaemic heart disease different?

Atherosclerosis: Atheroma is the lesion in a blood vessel caused by athrosclerosis. The disease and its atheromas cause ischemic heart disease by decreasing blood flow to the heart.

Definitions : An atheroma is a collection of cholesterol and fatty deposits within the wall of a blood vessel. This causes an inflammatory reaction that your body "attacks" and causes hardening of the wall over time. This hardening is called atherosclerosis. Ischemic heart disease is a general term for the variety of conditions that cause poor flow to the heart and their associated symptoms.