slur vs blotch

slur and blotch both are nouns.

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

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

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

slur (noun)	blotch (noun)
a blemish made by dirt	an irregularly shaped spot
a disparaging remark
(music) a curved line spanning notes that are to be played legato

slur (verb)	blotch (verb)
become vague or indistinct	mark with spots or blotches of different color or shades of color as if stained
utter indistinctly
speak disparagingly of; e.g., make a racial slur
play smoothly or legato