hematologist vs haematologist

hematologist and haematologist both are nouns.

Word	Noun	Adjective	Verb	Adverb
hematologist	Yes	No	No	No
haematologist	Yes	No	No	No

As nouns, hematologist and haematologist are synonyms defined as:

hematologist and haematologist: a doctor who specializes in diseases of the blood and blood-forming organs

hematologist (noun)	haematologist (noun)
a doctor who specializes in diseases of the blood and blood-forming organs	a doctor who specializes in diseases of the blood and blood-forming organs