smudge vs blotch

smudge and blotch both are nouns.

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

As nouns, blotch is a hyponym of smudge; that is, blotch is a word with a more specific, narrower meaning than smudge:

Other hyponyms of smudge include splodge, splotch, fingermark, fingerprint, inkblot.

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

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