Physically, the guns are no different. Use whatever mags you want in accordance with your local laws.
Other than the mags, differences are usually in marketing and packaging. There is nothing on the gun itself indicating it was sold as a CA compliant gun.
Once the gun is approved in CA, it is an involved process to change anything, down to color and sku. Some companies put up with it, others just maintain a separate product line, most just sell guns elsewhere.
