Mike,
Besides the fact that it is 1/4" stock, verses 3/16" on the full tang model CC/FT, The #15 is deeper, longer and has a plethora of options available not available on the CC/FT. Handle shapes, materials thumb notches, single hilts, besides the sawteeth...no teeth grind or standard on blade shaping are available for the #15 but not the CC/FT. Model A or C sheaths also can be had on the #15.
Some of the differences,
Best, Capt. Chris