sex chromosome vs XYY

sex chromosome and XYY both are nouns.

Word	Noun	Adjective	Verb	Adverb
sex chromosome	Yes	No	No	No
XYY	Yes	No	No	No

As nouns, XYY is a hyponym of sex chromosome; that is, XYY is a word with a more specific, narrower meaning than sex chromosome:

sex chromosome: (genetics) a chromosome that determines the sex of an individual
XYY: (genetics) abnormal complement of sex hormones in a male who has two Y chromosomes

Other hyponyms of sex chromosome include X chromosome, XX, XXX, XXY, XY, Y chromosome.

sex chromosome (noun)	XYY (noun)
(genetics) a chromosome that determines the sex of an individual	(genetics) abnormal complement of sex hormones in a male who has two Y chromosomes