Aside from the glaring differences pointed out by ODG(and others), Superboy Prime--the guy who later appeared in IC/SCW--didn't make his first official appearance until DC Comics Presents #87, released in 1985. The planet-towing feat occurred in Superboy v1 #140, released in 1967.
ie. Prime wasn't even a twinkle in DC's eye back when SA Superboy was casually towing dozens of planets across galactic distances, and flying several hundred thousand times the speed of light.
Simple, no?