underlay vs underfelt

underlay and underfelt both are nouns.

Word	Noun	Adjective	Verb	Adverb
underlay	Yes	No	Yes	No
underfelt	Yes	No	No	No

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

underlay (noun)	underfelt (noun)
a pad placed under a carpet	a carpet pad of thick felt

underlay (verb)	underfelt (verb)
provide with a base, support, lining, or backing
put (something) under or beneath
raise or support (the level of printing) by inserting a piece of paper or cardboard under the type