A Flyback chronograph is a complication watch, which uses a single push of the button for stopping, resetting and restarting the chronograph function of the watch.
Other names: Taylor system, Permanent zero setting
See more at http://en.wikipedia.org/wiki/Flyback_chronograph
A Double chronograph is a watch that includes two separate stopwatch mechanisms in order to estimate two separate events of different durations. It is often confused with the flyback chronograph.
Other names: Split-second chronograph, Split chronograph
See more at http://en.wikipedia.org/wiki/Double_chronograph
In horology (study of clocks), complication refers to any feature in a timepiece beyond the simple display of hours and minutes. A timepiece indicating only hours and minutes is otherwise known as a simple movement.