The CPU in the BlizzardPPC (for A1200) is a first or possibly second generation PowerPC.
The one in the CyberstormPPC (for A3000/A4000) is a second generation PowerPC.
The third generation was the PPC740, but the name "G3" kinda stuck and now applies to all CPUs that are more or less compatible with the 740. The 7400 was the G4, introducing Altivec. IBM has never used Altivec until now, but their POWER series (which is another derivation from the same basic theory behind PowerPC) has had a different SIMD (Single Instruction, Multiple Data) implementation. For their next "G3" they are looking at including an Altivec compatible SIMD unit, and they also use this on the so called "G5", which is a customised POWER4 cpu made for the desktop market.
The single, most confusing piece of all this is that non-technical people only look at the number after the G and think they know everything from that. But you really can't compare a PPC740 at 250MHz with a PPC750FX@800MHz or more. It just isn't fair.
It's almost like Intel changing the core of the Celeron from P2 to P3 then P4. You need to know not only what it's _called_, you need to know the excact core number/name and the frequency to really say anything specific...