Yes there is a great difference. A Capri 22 is more of a racing boat. The deck space is more open on a Capri and the cabin on the Catalina 22 is more for the cruiser type. ie. table, some stoves and sinks etc.The Capri 22 doesn't have all that stuff below. The Capri boom is much lower and the traveler is in the cockpit instead of on the stern rail. Those are just some of the differences.
The Capri 22 is more for racing and performance, whereas the Catalina 22's primary mission is bay cruising. The Capri 22 isn't the fastest racer, but I think it is the best bang for the buck.Spinnaker PHRF rating for the Capri 222 is approx. 200-220, whereas it is around 260-280 for the Catalina...Thus the Capri 22 is approx. 60 seconds a mile faster than the Catalina 22. Also, the Capri 22 is rigged like a J/24 one-design racer (spinnaker PHRF around 175), whereas the Catalina 22 is more "family friendly". Note for example the location of the mainsheet and traveler.
Yes there may only be approx. 850 Capri 22s compared to 15,000 Catalina 22s...all that says is that more folks buy this boat to cruise than to race. I used to own a Moore 24 and only about 150 of them were made, so 850 is more than enough to have worked the bugs out. I also crew on J/24s raced one-design. This means the first boat to finish wins (i.e., you don't have to figure out corrected times like PHRF). First to finish is the chief advantage of buying a one-design to race. I don't know where you live but I would imagine there are more Capri 22s in SoCal and Florida because thats where they're made. So...if you want to race and don't mind PHRF a Capri 22 is a good all-around boat. If all you want to do is cruise then the Catalina 22 is hard to beat.