stick-in-the-mud vs dawdler

stick-in-the-mud and dawdler both are nouns.

Word	Noun	Adjective	Verb	Adverb
stick-in-the-mud	Yes	Yes	No	No
dawdler	Yes	No	No	No

As nouns, dawdler is a hypernym of stick-in-the-mud; that is, dawdler is a word with a broader meaning than stick-in-the-mud:

stick-in-the-mud: someone who moves slowly
dawdler: someone who takes more time than necessary; someone who lags behind

Other hypernyms of stick-in-the-mud include drone, laggard, lagger, poke, trailer.

stick-in-the-mud (noun)	dawdler (noun)
someone who moves slowly	someone who takes more time than necessary; someone who lags behind

stick-in-the-mud (adjective)	dawdler (adjective)
(used pejoratively) out of fashion; old fashioned