Arthritis is an umbrella term used to describe pain, stiffness and inflammation of the joints. However, there are different kinds of arthritis, including rheumatoid arthritis (RA) and osteoarthritis (OA). Although RA and OA both affect the joints, they are very different forms of the same broader condition.Rheumatoid arthritis is an autoimmune condition, while osteoarthritis is a degenerative joint disease.lthough RA and OA both affect the joints, they are very different forms of the same broader condition. Rheumatoid arthritis is an autoimmune condition, while osteoarthritis is a degenerative joint disease.