The main difference between rheumatoid arthritis and osteoarthritis is the cause behind the joint symptoms, states the Mayo Clinic. In rheumatoid arthritis, an autoimmune disease, the body attacks itself by targeting the joints, whereas in osteoarthritis, the most common form of arthritis, mechanical wear and tear on joints causes the condition.
Other differences between the two diseases include the age and speed of the disease onset, joint symptoms, the type of joints affected, the duration of morning stiffness, and the presence of systemic symptoms, adds the Mayo Clinic. For rheumatoid arthritis, the condition starts at any time in life, progressing rapidly over a few weeks or months, and it causes painful, stiff and swollen joints. In contrast, osteoarthritis starts much later in life, progressing slowly over years; although it causes joint pain, there is little or no swelling.
Furthermore, rheumatoid arthritis affects the small and large joints in a symmetrical manner, causes morning stiffness that lasts for longer than one hour and has systemic symptoms, such as frequent fatigue and malaise, notes the Mayo Clinic. Conversely, osteoarthritis usually affects joints on one side of the body with symptoms limited to one set of joints, causes morning stiffness that lasts less than an hour and has no systemic symptoms.