tremolo vs vibrato

tremolo and vibrato both are nouns.

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

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

tremolo: vocal vibrato especially an excessive or poorly controlled one
vibrato: (music) a pulsating effect in an instrumental or vocal tone produced by slight and rapid variations in pitch

tremolo (noun)	vibrato (noun)
vocal vibrato especially an excessive or poorly controlled one	(music) a pulsating effect in an instrumental or vocal tone produced by slight and rapid variations in pitch
(music) a tremulous effect produced by rapid repetition of a single tone or rapid alternation of two tones