I could be off base, but I believe SE stood for "Special Edition" with differnet build kits then published, and in general were not really shipped to dealers, but rather magazines, and pros for testing, reviews, and photos. It seems like it was their internal system of managing the introduction. There could be subtle changes for sure, likely build...I know that VERY late 2013 some shops got Enduro 29er's and that the Experts were coming with a 2x10 drivetrain and a Fox fork(I'd guess these were the 2013.5SE), then it seemed like they suddenly also had the "2014" version with the Pike and X01. In their archive pages they don't even list a Enduro 29 in 2013 anymore, which is the reality of when things started being available to the general public. My S-works frame box and bike doesn't say anything but 2014.