Airtricity % discount - what is it based on?

Hi just wondering if anyone can explain this to me cause i'm totally confused!

i switched to bord gais for electricity and gas and was told i was getting a 14% discount (both fuels and direct debit).

on airtricity's website they are advertising a 10% saving on gas and 13% on electricity.

Is this on top of borg gais's 14%? or based on esb? if so i would be saving more with bord gais?

Any discounts offered by BG or Airtricity are compared with ESB's rates.

It's stated in their T&Cs, electricity rates are discouted below ESB standard rate, gas rates below Bord Gais' standard rate.
Leo