Other than the chamber load indicator and mag disconnect, Microstamping,There should be no other difference

The california version has a bunch of extra "safety" features that drive up the price such as a thumb safety and a magazine safety.

This version is not sold on the incredibly large scale the standard version is. Thus with less being produced, the price must go up to offset production and setup costs. In other words, the more you sell the lower the price, and vice versa. This model has many subtle differences. This M&P comes with a $75 mail in rebate valid until June 30th. This may help offset that $100 increase.

I know magazine capacity and also the materials used to make the pistol have to be a bit different. CA Compliant firearms cannot have too much zinc or other metals that have a melting point below around 1,000 degrees F because they are worried about people being able to melt them down (that's why Hi Point isn't approved). I think there is also the extra certification fees they incur to get their items approved and these are for sure passed on to us, the customer, unfortunately.