The Lawman was a later design that was built with more "modern" manufacturing methods.
It used cheaper-to-make key parts (hammer, trigger, hand, etc.) requiring a lesser (or no) amount of hand fitting.
Can't be tuned quite like the DS.
Was the fixed-sight version of the Trooper MKIII action.
More durable action overall than the DS, but when something wears out it typically requires finding a new part that already fits, as opposed to a new part that's fitted individually in the DS.
Trigger could break around the pivot pin, like the full-sized version, but that wasn't common.
D should be along shortly to say the Trooper MKIII/Lawman frames themselves were quite strong.
Aside from that, you're comparing a .38 to a .357 Mag, as noted above.
Denis