What is the difference between a Chronometer and a Chronograph?
A chronograph and chronometer are two very different things, despite their similar sounding titles.
A chronograph is a feature on a watch that allows you to measure elapsed time, almost like a stop watch on the wrist. Chronographs can come in many different styles, with some watches having two or three sub dials. Chronograph watches are distinctive not only by their sub dials but also from the buttons found on the side of their case which control the stopwatch features. You can find some examples of chronograph watches here.
A chronometer, on the other hand, refers to an official certification. If a watch is a chronometer it has passed an intense range of tests over a 15 day period and obtained an official COSC certificate, also known as the Official Swiss Chronometer Testing Institute. This certification validates the watch as having a high standard of accuracy, since in order to receive such a qualification the watch must remain within the +6 and -4 seconds per day. If you are looking for a timepiece that is exceptionally reliable, then look out for this COSC certificate. You can find some examples of COSC certified watches here.