If the calculated fault current is 22,000A, it is typically a three phase bolted fault value.
A breaker listed as 22kAIC is theoretically more robust than one listed at 10kAIC. Sometimes it is a marketing and liability issue though. I've heard of breakers that are manufactured with a 22kAIC rating, then relabeled also for sale as 10kAIC, so the manufacturer has one manufacturing process and pays a lower liability insurance on the 10kAIC breaker. It works out cost effective for the manufacturer.
