In looking at the SA Mil-spec 1911s, there are"CA Compliant" versions. They are about $100 more and appearance wise, the only difference I see are the grips. What exactly is the difference? Thank you.

They have jumped through the hoops for drop safety testing and have bribed all of the right CA departments to 'put them on the list' and allow the sale in CA.  I believe the destruction of 5 samples has to occur and the manufacturer has to pay for it, which means the consumer also has to pay for it.

I am going to bet the variants are series 80 style inner works.  I doubt a series 70 would pass drop testing.

The CA compliant models have the ILS system, which is the little key thing that locks the hammer strut in the mainspring housing, sort of like a Hillary hole on a S&W revolver. It can be removed with a new MSH and strut assembly.

Springfield uses titanium .38 super firing pins and a strong FP spring to pass the drop safety tests. They use a Series 70 FCG.