A watchmaker is one who primarily repairs watches, although historically this person also made watches. A contemporary, well-trained watchmaker is more likely to be able to repair a wristwatch or a pocketwatch than to actually build or manufacture a watch from scratch. Watchmakers can typically manufacture many of the parts found in a wristwatch or a pocketwatch.
A watchmaker, as the name infers, works primarily on watches, not clocks. Some watchmakers work on clocks, but the skills and tools needed to work on a watch aren't always applicable when working on a clock.
Watchmaker as metaphor
William Paley used the watch to infer argument from design for the existence of God; hence God is the watchmaker. Richard Dawkins later applied this analogy in his book The Blind Watchmaker, arguing that evolution, the source of origins, is blind in that it cannot look forward.