blotch vs smudge

blotch and smudge both are nouns.

Word	Noun	Adjective	Verb	Adverb
blotch	Yes	No	Yes	No
smudge	Yes	No	Yes	No

As nouns, smudge is a hypernym of blotch; that is, smudge is a word with a broader meaning than blotch:

Other hypernyms of blotch include blot, daub, slur, smear, smirch, spot.

blotch (noun)	smudge (noun)
an irregularly shaped spot	a blemish made by dirt
	a smoky fire to drive away insects

blotch (verb)	smudge (verb)
mark with spots or blotches of different color or shades of color as if stained	make a smudge on; soil by smudging