soiling vs staining

soiling and staining both are nouns.

Word	Noun	Adjective	Verb	Adverb
soiling	Yes	No	No	No
staining	Yes	No	No	No

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

Other hyponyms of soiling include maculation, spotting, contamination, pollution.

soiling (noun)	staining (noun)
the act of soiling something	(histology) the use of a dye to color specimens for microscopic study
	the act of spotting or staining something