fatigue vs jet lag

fatigue and jet lag both are nouns.

Word	Noun	Adjective	Verb	Adverb
fatigue	Yes	No	Yes	No
jet lag	Yes	No	No	No

As nouns, jet lag is a hyponym of fatigue; that is, jet lag is a word with a more specific, narrower meaning than fatigue:

fatigue: temporary loss of strength and energy resulting from hard physical or mental work
jet lag: fatigue and sleep disturbance resulting from disruption of the body's normal circadian rhythm as a result of jet travel

Other hyponyms of fatigue include asthenopia, eyestrain, exhaustion, grogginess, logginess, loginess, senioritis.

fatigue (noun)	jet lag (noun)
labor of a nonmilitary kind done by soldiers (cleaning or digging or draining or so on)	fatigue and sleep disturbance resulting from disruption of the body's normal circadian rhythm as a result of jet travel
(always used with a modifier) boredom resulting from overexposure to something
temporary loss of strength and energy resulting from hard physical or mental work
used of materials (especially metals) in a weakened state caused by long stress

fatigue (verb)	jet lag (verb)
exhaust or get tired through overuse or great strain or stress
lose interest or become bored with something or somebody