3SGTE generations

What is the differance in the generation 2 and 3 3SGTE? Were their any internal engine changes? I am not very concerned with the turbo.

Here is some basic data:
http://www.geocities.com/MotorCity/Pit/9975/dataBySubject/GasolineEngines.html#S-series

2nd gen
hp - 225
turbo - ct26
c/r - 8.1:1
psi - 11.0
3rd gen
hp - 245
turbo - ct20b
c/r - 8.5:1
psi - 13