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.
Even if they are equals, Jason has been training his whole life, while Percy has only been training for the summers of 4-5 years.
Percy's feats are greater too. Jason became praetor of New Rome and defeated Krios, but Percy defeated the Minotaur and all three Gorgons, sailed through the Sea of Monsters, held the sky, found his way in the Labyrinth, fought Zeus, survived in Tartarus, defeated Ares in a sword fight, etc.