Both Hodgkin's lymphoma and non-Hodgkin's lymphoma are lymphomas — a type of cancer that begins in a subset of white blood cells called lymphocytes. Lymphocytes are an integral part of your immune system, which protects you from germs. The main difference between Hodgkin's and non-Hodgkin's lymphoma is in the specific lymphocyte each involves. A doctor can tell the difference between Hodgkin's and non-Hodgkin's 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's.