Generally,the main difference would be that the SR-21 is an insurance proof form, whilst the SR-22 is recognized as to be future proof of financial responsibility.
The SR-21 is generally needed after a car accident to make sure that you had auto insurance coverage during the time of the actual car accident. Florida, Georgia, and Indiana are a couple of the states which use a SR-21 form in order to confirm insurance (for different reasons). The SR-21 is common for the state of Indiana’s SR-21, Certificate of Compliance.
In this state, any driver that’s involved in an car crash leading to injury, death, or property damage more than $1,000 is liable for having his insurance carrier electronically send the SR-21 (proof of insurance accident report). The form certifies that the motorist was covered on the day of the automobile accident and has to be presented to the Indiana Bureau of Motor Vehicles (BMV) within ten days of the automobile accident.
The SR-22 is a certification of financial responsibility which are required as part of the procedure to restore your licence after a revocation for a major violation (i.e. Drunk driving) or after specific convictions (i.e. operating without insurance coverage).