ankylosing spondylitis vs rheumatoid spondylitis

ankylosing spondylitis and rheumatoid spondylitis both are nouns.

Word	Noun	Adjective	Verb	Adverb
ankylosing spondylitis	Yes	No	No	No
rheumatoid spondylitis	Yes	No	No	No

As nouns, ankylosing spondylitis and rheumatoid spondylitis are synonyms defined as:

ankylosing spondylitis and rheumatoid spondylitis: a chronic form of spondylitis primarily in males and marked by impaired mobility of the spine; sometimes leads to ankylosis

Other synonyms of ankylosing spondylitis include Marie-Strumpell disease.

ankylosing spondylitis (noun)	rheumatoid spondylitis (noun)
a chronic form of spondylitis primarily in males and marked by impaired mobility of the spine; sometimes leads to ankylosis	a chronic form of spondylitis primarily in males and marked by impaired mobility of the spine; sometimes leads to ankylosis