They look virtually identical and I would suspect that their performance is very similar (if not identical). You could also add this to either to enhance the cooling capacity:http://www.arctic.ac/en/p/cooling/vga/457/s1-plus-turbo-module.html?c=2182
I actually used an S1 Plus with an older GPU a couple of years ago. It actually worked well and was dead silent (as expected).
Save your money and get the less expensive of the 2 VGA coolers.