monocyte vs white cell

monocyte and white cell both are nouns.

Word	Noun	Adjective	Verb	Adverb
monocyte	Yes	No	No	No
white cell	Yes	No	No	No

As nouns, white cell is a hypernym of monocyte; that is, white cell is a word with a broader meaning than monocyte:

monocyte: a type of granular leukocyte that functions in the ingestion of bacteria
white cell: blood cells that engulf and digest bacteria and fungi; an important part of the body's defense system

Other hypernyms of monocyte include leucocyte, leukocyte, WBC, white blood cell, white blood corpuscle, white corpuscle.

monocyte (noun)	white cell (noun)
a type of granular leukocyte that functions in the ingestion of bacteria	blood cells that engulf and digest bacteria and fungi; an important part of the body's defense system