can someone explain the difference between a standard mauser action and a double square bridge type?

In the era before mass produced scope mounts, Mauser offered some of their commercial 98's with single or double square bridges so that gunsmiths could more easily fit Suhler style (SEM) rings and bases. Because of their rarity, they command premium prices.

so the square bridge means integral scope bases, as in the cz?
this is what makes it considered a square bridge?

thanks!

The post-1950 Brno and CZ rifles have square bridges that are already machined for scope rings that fit on a 19mm dovetail. The orginal Mauser square bridges are blank, they can be machined for whatever rings or mounts a gunsmith chooses to use.