time of day vs clock time

time of day and clock time both are nouns.

Word	Noun	Adjective	Verb	Adverb
time of day	Yes	No	No	No
clock time	Yes	No	No	No

As nouns, clock time is a hypernym of time of day; that is, clock time is a word with a broader meaning than time of day:

Other hypernyms of time of day include time.

time of day (noun)	clock time (noun)
clock time	a reading of a point in time as given by a clock