tremolo vs quivering

tremolo and quivering both are nouns.

Word	Noun	Adjective	Verb	Adverb
tremolo	Yes	No	No	No
quivering	Yes	No	No	No

As nouns, quivering is a hypernym of tremolo; that is, quivering is a word with a broader meaning than tremolo:

tremolo: (music) a tremulous effect produced by rapid repetition of a single tone or rapid alternation of two tones
quivering: a shaky motion

Other hypernyms of tremolo include palpitation, quiver, shakiness, shaking, trembling, vibration.

tremolo (noun)	quivering (noun)
vocal vibrato especially an excessive or poorly controlled one	the act of vibrating
(music) a tremulous effect produced by rapid repetition of a single tone or rapid alternation of two tones	a shaky motion