groom vs neaten

groom is a noun but neaten is not a noun.

Word	Noun	Adjective	Verb	Adverb
groom	Yes	No	Yes	No
neaten	No	No	Yes	No

As verbs, groom and neaten are synonyms defined as:

groom (noun)	neaten (noun)
a man who has recently been married
someone employed in a stable to take care of the horses
a man participant in his own marriage ceremony

groom (verb)	neaten (verb)
care for one's external appearance	care for one's external appearance
give a neat appearance to	put (things or places) in order
educate for a future role or function