Can you spot the differences between these two tires?
The one on the left is a 265/65/17 LT2 x-Radial and the one on the right is the M/S2. The LT2, it looks like, is not limited to a 'store brand' per se, but maybe a costco specific brand?!
The Michelin LTX M/S2 is a great tire. I've got it myself. In fact I've used the LTX M/S for years and the M/S2 is a better tire (costs more too!) The difference (in the picture) is the Michelin has superior siping and (I believe) it has more tread depth. A person can have the tire siped but I wouldn't mess with the tires. I did it once in Montana and it improved the tire, but I don't think I would do it again.
Looks like they are both good tires; but I would go with the Michelins. The Michelin gives a very comfortable ride on black top; it has a wider footprint then most tires and they are good in snow/water/dirt. On dirt it is good but not as good as a tire like the Toyo Open Country or any tire built for dirt roads. Off-road tires are whole different ball game.
Discount Tires is one of the best places to get tires and warranties imo.