surface soil vs dirt

surface soil and dirt both are nouns.

Word	Noun	Adjective	Verb	Adverb
surface soil	Yes	No	No	No
dirt	Yes	Yes	No	No

As nouns, dirt is a hypernym of surface soil; that is, dirt is a word with a broader meaning than surface soil:

surface soil: the layer of soil on the surface
dirt: the part of the earth's surface consisting of humus and disintegrated rock

Other hypernyms of surface soil include soil.

surface soil (noun)	dirt (noun)
the layer of soil on the surface	disgraceful gossip about the private lives of other people
	anything regarded as making something unclean
	the part of the earth's surface consisting of humus and disintegrated rock
	obscene terms for feces

surface soil (adjective)	dirt (adjective)
	(of roads) not leveled or drained; unsuitable for all year travel