RBC vs blood corpuscle

RBC and blood corpuscle both are nouns.

Word	Noun	Adjective	Verb	Adverb
RBC	Yes	No	No	No
blood corpuscle	Yes	No	No	No

As nouns, blood corpuscle is a hypernym of RBC; that is, blood corpuscle is a word with a broader meaning than RBC:

RBC: a mature blood cell that contains hemoglobin to carry oxygen to the bodily tissues; a biconcave disc that has no nucleus
blood corpuscle: either of two types of cells (erythrocytes and leukocytes) and sometimes including platelets

Other hypernyms of RBC include blood cell, corpuscle.

RBC (noun)	blood corpuscle (noun)
a mature blood cell that contains hemoglobin to carry oxygen to the bodily tissues; a biconcave disc that has no nucleus	either of two types of cells (erythrocytes and leukocytes) and sometimes including platelets