modulation vs droning

modulation and droning both are nouns.

Word	Noun	Adjective	Verb	Adverb
modulation	Yes	No	No	No
droning	Yes	No	No	No

As nouns, droning is a hyponym of modulation; that is, droning is a word with a more specific, narrower meaning than modulation:

Other hyponyms of modulation include intonation pattern, drone, monotone, singsong.

modulation (noun)	droning (noun)
the act of modifying or adjusting according to due measure and proportion (as with regard to artistic effect)	an unchanging intonation
(electronics) the transmission of a signal by using it to vary a carrier wave; changing the carrier's amplitude or frequency or phase
a musical passage moving from one key to another
rise and fall of the voice pitch
a manner of speaking in which the loudness or pitch or tone of the voice is modified