Basically just the movement, although over time the text on the dial changed a little too. Early ones just said "B-1", while later models had "Chronometre Certifie" (or something similar) on the dial.
SQ, with it's thermal compensation technology, is more accurate but when you consider how accurate quartz is anyway, it's all a bit redundant IMHO. The pros of SQ over standard quartz are simply the accuracy - i.e. a few seconds a year against a few more seconds a year. Yes it's very cool, but in practical terms I personally don't see the huge benefit...... but then I'm used to autos where accuracy to a few seconds a day is considered a good thing!
