Easy to remember. 38/357 are "small frame" with square tang for grips. 44 spl/44mag are "large frame" and have oval tangs for the grips. Model 14 has fixed rear sight and 'pork chop" barrel shroud. Model 15 have adjustable rear sights and straight barrel shrouds.Small Frame, Large Frame, Square Tang, Round Tang…. My head hurts. I’m guessing you guys have large frame and square tang pistols.
Both have removable barrel shrouds and barrels. You actually set the cylinder gap when you change barrels (very easy).