Confused about the difference between osteoarthritis & rheumatoid arthritis?

Osteoarthritis vs. rheumatoid arthritis

The two most common types of arthritis affect joints in very different ways. In osteoarthritis, the cartilage on the ends of the bones wears away — allowing bone to grate on bone. Rheumatoid arthritis is an autoimmune disorder that causes inflammation of the synovial membrane and may result in bone loss.