Here are some examples of how the ENY score comes in to play:
You are in a F6F w/ an ENY of 15 and you shoot down an enemy Spitfire Mk XVI (Spit16) w an ENY of 5. You just earned 3 perk points. Oh, but wait. Your country has a higher ratio of players comparatively and the modifier is .89 (shown on the hanger on the clipboard). So take your 3 perk points you just earned and you get %89 of that, so your new score is 2.67 perk points.
Later on in the day....
You are in a P51D (5 ENY) and you get a kill on a P40B (40ENY), you just earned .125 perks for that kill. Oh, but wait. Your country is out numbered comparatively and has a 1.29 ENY modifier. You new perk point award is: .161 perks.
The name of the game is the more gifted the plane is that you fly the less you earn in perk points.
OBJ scores work the same way but instead of earning perk points for shooting down a player, you earn perk points for destroying "OBJ" (objects), namely buildings, hangers, ammo bunkers, radar, fuel tanks, barracks, ack guns, etc.