Joseph, both are Double Stack Sir. Most manufacturers including S&W make firearm packages that have 10rd magazines so their pistols can also be sold in state that have magazine capacity restrictions. The pistols are exactly the same but just have 10rd mags included. The pistols will also accept any standard capacity magazines and vice versa for the higher capacity magazine model accepting the 10rd magazine.

no they are both double stack the 10 round mag is just a modified (blocked) 16 round mag so they can sell the gun in states that have a 10 round magazine restriction. the mags are interchangeable