Focusrite ISA 220 Session Pack vs Focusrite ISA 430 Producer Pack?

[Judas]

I'm thinking of buying a really good Mic Pre amp, does anyone know (or hear) the diffrence between Focusrite ISA 430 Producer Pack and Focusrite ISA 220 Session Pack? (I dont, really)

Could somebody tell me the difference, is it worth the extra $1500?