histiocytosis vs blood disorder

histiocytosis and blood disorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
histiocytosis	Yes	No	No	No
blood disorder	Yes	No	No	No

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

histiocytosis: a blood disease characterized by an abnormal multiplication of macrophages
blood disorder: a disease or disorder of the blood

Other hypernyms of histiocytosis include blood disease.

histiocytosis (noun)	blood disorder (noun)
a blood disease characterized by an abnormal multiplication of macrophages	a disease or disorder of the blood