15-22 has a mil-spec tube. Mil-spec stocks fit a 15-22 just fine. Both the MOE mil-spec and CTR mil-spec fit on a 15-22 just as they would an AR mil-spec tube. The CTR has a friction lock that binds it tightly to the tube when engaged so there is no wiggle at all. The MOE has no friction lock.
"Commercial" is just slightly larger in diameter than mil-spec. So to answer your question.... a commercial (larger) stock will fit on a mil-spec (smaller) tube though somewhat sloppy. A mil-spec stock (smaller) will not fit on a commercial (larger) tube. I know a guy who bought a commercial CTR for his AR because it has a commercial tube. However, he sometimes throws it on his 15-22. The friction lock on the commercial CTR keeps it fairly tight on his 15-22.... though not as tight as it should be as on his AR.
In any event... if the stock is for the 15-22 get the mil-spec.
Here's a pic of a CTR.