kt-120 or kt-88?

Hay every one I am seeing more and more people go with kt-120 power tubes with there tube amps.

Whats the difference between the kt-120 output tubes vs the kt-88's?
Is it true that the kt-120 gives more power for your speakers too run?

I have a tube class A Triode power amp and can run the kt-120s but are they that better then the regular kt-120.

Whats your experience and thoughts of this tubes?