undertone vs tone

undertone and tone both are nouns.

Word	Noun	Adjective	Verb	Adverb
undertone	Yes	No	No	No
tone	Yes	No	Yes	No

As nouns, tone is a hypernym of undertone; that is, tone is a word with a broader meaning than undertone:

Other hypernyms of undertone include shade, tincture, tint.

As nouns, tone is a hypernym of undertone; that is, tone is a word with a broader meaning than undertone:

Other hypernyms of undertone include tone of voice.

undertone (noun)	tone (noun)
a pale or subdued color	a quality of a given color that differs slightly from another color
a subdued emotional quality underlying an utterance; implicit meaning	(music) the distinctive property of a complex sound (a voice or noise or musical sound)
a quiet or hushed tone of voice	(linguistics) a pitch or change in pitch of the voice that serves to distinguish words in tonal languages
	the quality of something (an act or a piece of writing) that reveals the attitudes and presuppositions of the author
	a steady sound without overtones
	a musical interval of two semitones
	the quality of a person's voice
	a notation representing the pitch and duration of a musical sound
	the general atmosphere of a place or situation and the effect that it has on people
	the elastic tension of living muscles, arteries, etc. that facilitate response to stimuli

undertone (verb)	tone (verb)
	give a healthy elasticity to
	change to a color image
	change the color or tone of
	utter monotonously and repetitively and rhythmically
	vary the pitch of one's speech