timepiece vs sandglass

timepiece and sandglass both are nouns.

Word	Noun	Adjective	Verb	Adverb
timepiece	Yes	No	No	No
sandglass	Yes	No	No	No

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

timepiece: a measuring instrument or device for keeping time
sandglass: timepiece in which the passage of time is indicated by the flow of sand from one transparent container to another through a narrow passage

Other hyponyms of timepiece include atomic clock, clock, sundial, timer, ticker, watch.

timepiece (noun)	sandglass (noun)
a measuring instrument or device for keeping time	timepiece in which the passage of time is indicated by the flow of sand from one transparent container to another through a narrow passage