undersurface vs sole

undersurface and sole both are nouns.

Word	Noun	Adjective	Verb	Adverb
undersurface	Yes	No	No	No
sole	Yes	Yes	Yes	No

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

Other hyponyms of undersurface include base, bilge, heel, underbelly.

undersurface (noun)	sole (noun)
the lower side of anything	right-eyed flatfish; many are valued as food; most common in warm seas especially European
	the underside of footwear or a golf club
	the underside of the foot
	lean flesh of any of several flatfish

undersurface (adjective)	sole (adjective)
	being the only one; single and isolated from others
	not divided or shared with others

undersurface (verb)	sole (verb)
	put a new sole on