The higher the efficiency rating, the better the ship is at transporting wares. This is mainly a useful number for deciding which TS to use for universe traders. The default value is for the standard cargo capacity of a newly bought ship, while the max value is for a cargo space-maxed ship.
Formula to calculate the transport efficiency: ship's max speed * cargo capacity / 1,000
Hangar cost efficiency:
The higher the efficiency rating, the more fighters you get for the ship's price. Mainly useful when you want to use carriers as defensive or offensive forces.
Formula to calculate the hangar cost efficiency: ship's hangar size * 1,000,000,000 / price