reticulocyte vs red blood cell

reticulocyte and red blood cell both are nouns.

Word	Noun	Adjective	Verb	Adverb
reticulocyte	Yes	No	No	No
red blood cell	Yes	No	No	No

As nouns, red blood cell is a hypernym of reticulocyte; that is, red blood cell is a word with a broader meaning than reticulocyte:

reticulocyte: an immature red blood cell containing a network of filaments or granules
red blood cell: a mature blood cell that contains hemoglobin to carry oxygen to the bodily tissues; a biconcave disc that has no nucleus

Other hypernyms of reticulocyte include erythrocyte, RBC.

reticulocyte (noun)	red blood cell (noun)
an immature red blood cell containing a network of filaments or granules	a mature blood cell that contains hemoglobin to carry oxygen to the bodily tissues; a biconcave disc that has no nucleus