Glomerulonephritis is the term used when the glomeruli become inflamed. This means that the blood is less able to pass through the blood vessels in the glomerulus and so the kidneys cannot make as much urine as usual.
Chronic renal failure (CRF) is a term used when the kidneys are not working as well as they should. The term implies that both kidneys are affected. This is because one normal kidney is enough to maintain normal kidney function throughout life.