speaking vs whispering

speaking and whispering both are nouns.

Word	Noun	Adjective	Verb	Adverb
speaking	Yes	Yes	No	No
whispering	Yes	Yes	No	No

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

Other hyponyms of speaking include speech, susurration, voicelessness, whisper, voicelessness.

speaking (noun)	whispering (noun)
delivering an address to a public audience	speaking softly without vibration of the vocal cords
the utterance of intelligible speech	a light noise, like the noise of silk clothing or leaves blowing in the wind

speaking (adjective)	whispering (adjective)
capable of or involving speech or speaking	making a low continuous indistinct sound
capable of speech