canker sore vs ulceration

canker sore and ulceration both are nouns.

Word	Noun	Adjective	Verb	Adverb
canker sore	Yes	No	No	No
ulceration	Yes	No	No	No

As nouns, ulceration is a hypernym of canker sore; that is, ulceration is a word with a broader meaning than canker sore:

canker sore: an ulceration (especially of the lips or lining of the mouth)
ulceration: a circumscribed inflammatory and often suppurating lesion on the skin or an internal mucous surface resulting in necrosis of tissue

Other hypernyms of canker sore include ulcer.

canker sore (noun)	ulceration (noun)
an ulceration (especially of the lips or lining of the mouth)	the process of ulcer formation; the process of becoming ulcerated
	a circumscribed inflammatory and often suppurating lesion on the skin or an internal mucous surface resulting in necrosis of tissue