B-cell lymphoma refers to types of non-Hodgkin lymphoma that are characterised by abnormalities of the "B cells" (a type of white blood cell that makes antibodies to help fight infection). The condition may grow and spread slowly with few symptoms (also known as indolent lymphoma) or may be very aggressive with severe symptoms.
Non-Hodgkin lymphoma (also known as non-Hodgkin’s lymphoma, NHL, or sometimes just lymphoma) is a cancer that starts in white blood cells called lymphocytes, which are part of the body’s immune system. NHL is a term that's used for many different types of lymphoma that all share some of the same characteristics. NHL usually starts in lymph nodes or other lymph tissue, but it can sometimes affect the skin. Non-Hodgkin lymphoma is one of the most common cancers in the United States, accounting for about 4% of all cancers.
Relapsed refers to when a patient has received active treatment, went off treatment and then the disease came back, whereas refractory refers to disease that is progressing despite active treatment.