monotone vs pitch contour

monotone and pitch contour both are nouns.

Word	Noun	Adjective	Verb	Adverb
monotone	Yes	Yes	No	No
pitch contour	Yes	No	No	No

As nouns, pitch contour is a hypernym of monotone; that is, pitch contour is a word with a broader meaning than monotone:

Other hypernyms of monotone include intonation, modulation.

monotone (noun)	pitch contour (noun)
an unchanging intonation	rise and fall of the voice pitch
a single tone repeated with different words or different rhythms (especially in rendering liturgical texts)

monotone (adjective)	pitch contour (adjective)
of a sequence or function; consistently increasing and never decreasing or consistently decreasing and never increasing in value
sounded or spoken in a tone unvarying in pitch