The main difference between rheumatic fever and rheumatoid arthritis is that in addition to symptoms of arthritis, rheumatic fever also presents with elevated anti-streptolysin O levels and valvular heart disease, with some patients displaying subcutaneous erythema and chorea-like symptoms. Rheumatoid arthritis, on the other hand, primarily manifests as joint pain, and rarely involves heart valve issues. Additionally, rheumatoid arthritis is characterized by elevated rheumatoid factor, anti-CCP antibodies, and anti-AkA antibodies as its main clinical features. Patients with rheumatoid arthritis also exhibit increased inflammatory markers. The key differences between rheumatic fever and rheumatoid arthritis lie in the different antibodies involved and the general association of rheumatic fever with cardiac involvement.