The main difference between Lyme arthritis and rheumatoid arthritis is the cause. Lyme arthritis is caused by Lyme disease, a bacterial infection. Rheumatoid arthritis is an autoimmune condition where your immune system mistakenly attacks joint tissue.
Lyme disease may increase your risk of rheumatoid arthritis. A 2017 study details 30 people who went on to develop inflammatory arthritis, including rheumatoid arthritis, a median of 4 months after a Lyme disease diagnosis.