timekeeper vs sundial

timekeeper and sundial both are nouns.

Word	Noun	Adjective	Verb	Adverb
timekeeper	Yes	No	No	No
sundial	Yes	No	No	No

As nouns, sundial is a hyponym of timekeeper; that is, sundial is a word with a more specific, narrower meaning than timekeeper:

timekeeper: a measuring instrument or device for keeping time
sundial: timepiece that indicates the daylight hours by the shadow that the gnomon casts on a calibrated dial

Other hyponyms of timekeeper include atomic clock, clock, sandglass, timer, ticker, watch.

timekeeper (noun)	sundial (noun)
a measuring instrument or device for keeping time	timepiece that indicates the daylight hours by the shadow that the gnomon casts on a calibrated dial
a clerk who keeps track of the hours worked by employees
(sports) an official who keeps track of the time elapsed