Acute bacteria endocarditis is usually caused by S. Aureus and runs a very acute course (over weeks). Subacute bacterial endocarditis is by other "subtler" bacteria, usually Strep species such as Strep viridans (over months).
Rheumatic fever is a systemic inflammatory disease in response to Strep pyogenes infection. Basically the immune system tries to attack S. pyogenes but misfires and attacks other body parts instead due to their molecular mimicry (keyword
). Due to the auto-immune process your valves, joints, skin etc get damaged and present with carditis, erythema marginatum, arthritis etc.
Chronic rheumatic heart disease is what happens in some people 10-20 years after the initial rheumatic fever, and is a major cause of acquired valvular disease in the developing world. It usually manifests as valvular stenosis or regurgitation, and this is a result of long term inflammation of the myocardium.
(Yes I did refer to sources