The Superhero Database Classification number, or SHDB Class, is a number that represents the overall 'power' of a character. All traits of a character are used for calculating the Classification.
What it DOESN'T mean
This doesn't mean that a higher class would always beat a lower class character. But the bigger the difference in Class is, the more obvious it is who'll win in a fight.
How is this calculated
( INT^1.3 + (STR*0.5 )^2 + (SPE*0.5)^2 + DUR^1.6 + (POW + (SPS*SPL))^2 + COM^1.8 ) ^ TIER
Super Power Score and Level
Every Super Power has a score (SPS) that is used to calculate the Class. Each Super Power also has 3 levels (SPL). The level is set when connecting that Super Power to a character. The level determines the final score, of the Super Power, being used in the calculation.
1) While Superman-Prime was able to effect the entire New Earth's universe with his retcon punches as Superboy-Prime, Pre-Crisis Superman can easily do that while have a friendly spar with Jaxon, which isn't just the future timeline, but the entire future multiverse destroy by the Time Trapper.
2) Both are capable of surviving Big Bangs, except Pre-Crisis Superman can handle it much easier.
3) Superman-Prime never shown any signs of multiverse feats before becoming a Time Trapper; whereas Pre-Crisis Superman with his own power already shown signs of multiverse feats.
4) They both have immeasurable speed that's for certain.
5) While Superman-Prime has no weakness, Pre-Crisis Superman has the superior stats here with superior haxs.
6) Overall, I see this as a close fight, with Pre-Crisis Superman having the winning slight edge.