First of all, my theory is that Giant makes most if not all bicycles.
More to the point, I own a DS and am partial to it in this category where I shopped a lot a few years ago. But these two bikes you're considering are nearly identical component-wise. I strongly endorse riding them both. The DS has DuoTrap compatibility even at this price point, which I value, but you may not. To me, that's the only real distinguishing factor. Much More importantly: the DS2 black is The best color. Enjoy your riding and you'll enjoy the bike that feels best to you on the first ride.