backlog vs fuel level

backlog and fuel level both are nouns.

Word	Noun	Adjective	Verb	Adverb
backlog	Yes	No	Yes	No
fuel level	Yes	No	No	No

As nouns, fuel level is a hyponym of backlog; that is, fuel level is a word with a more specific, narrower meaning than backlog:

Other hyponyms of backlog include bank, reserve account, reserve fund, capital reserve.

backlog (noun)	fuel level (noun)
an accumulation of jobs not done or materials not processed that are yet to be dealt with (especially unfilled customer orders for products or services)	the amount of fuel remaining
something kept back or saved for future use or a special purpose
the large log at the back of a hearth fire

backlog (verb)	fuel level (verb)
accumulate and create a backlog