re-echo vs echo

re-echo and echo both are nouns.

Word	Noun	Adjective	Verb	Adverb
re-echo	Yes	No	No	No
echo	Yes	No	Yes	No

As nouns, echo is a hypernym of re-echo; that is, echo is a word with a broader meaning than re-echo:

re-echo: the echo of an echo
echo: the repetition of a sound resulting from reflection of the sound waves

Other hypernyms of re-echo include replication, reverberation, sound reflection.

re-echo (noun)	echo (noun)
the echo of an echo	an imitation or repetition
	the repetition of a sound resulting from reflection of the sound waves
	a reflected television or radio or radar beam
	a close parallel of a feeling, idea, style, etc.
	a reply that repeats what has just been said