I went in to my local Apple Store today because I suck at this whole college thing and just didn't feel like doing any homework (plus its too nice outside). Anyway, this was my second try-on appointment that I had, with my first one being last Friday. During this appointment, I noticed that the sensors on the Watch Sport are different than on the Watch. Can anybody speculate as to why? I know that the Watch Sport has a composite back and the Watch has a ceramic back, but why else would they be different?? Is one going to be more accurate than the other? I've also included a comparison photo between the 38mm, 42mm, and the Pebble for anybody that wants them, and some of the details from the settings app on the demo models just in case somebody was looking for that as well. Sorry those are sideways!