In nautical|lang=en terms the difference between watch and check
is that
watch is (nautical) a period of time on duty, usually four hours in length; the officers and crew who tend the working of a vessel during the same watch (fm 55–501) while
check is (nautical) to slack or ease off, as a brace which is too stiffly extended.
As nouns the difference between watch and check
is that
watch is a portable or wearable timepiece while
check is (chess) a situation in which the king is directly threatened by an opposing piece or
check can be (textiles|usually|pluralized) a pattern made up of a grid of squares of alternating colors; a checkered pattern.
As verbs the difference between watch and check
is that
watch is (
label) to look at, see, or view for a period of time while
check is to inspect; to examine.