Both Hodgkin lymphoma (formerly known as Hodgkin's disease) and non-Hodgkin lymphoma (also known as non-Hodgkin's lymphoma) are lymphomas, a type of cancer that originates in a subset of white blood cells called lymphocytes. Lymphocytes are an important part of your immune system. The main difference between Hodgkin and non-Hodgkin lymphoma is in the specific lymphocyte each involves.
A doctor can tell the difference between Hodgkin and non-Hodgkin lymphoma by examining the cancer cells under a microscope. If in examining the cells, the doctor detects the presence of a specific type of abnormal cell called a Reed-Sternberg cell, the lymphoma is classified as Hodgkin. If the Reed-Sternberg cell is not present, the lymphoma is classified as non-Hodgkin.
The distinction is important because the treatment for each type can be very different.