G30SF v G30 Gen4

I have an older G30 which was my first Glock that I really liked. Well I knew someone who also fell in love with it and he talked me out of it for a rifle.
Well I'm looking to replace it and on the Glock sight they list comparisons between the G30SF and the G30 Gen4. What is the difference between the two? I'm looking for the smallest .45ACP they have.
Thanks