clock time vs meter reading

clock time and meter reading both are nouns.

Word	Noun	Adjective	Verb	Adverb
clock time	Yes	No	No	No
meter reading	Yes	No	No	No

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

clock time: a reading of a point in time as given by a clock
meter reading: a datum about some physical state that is presented to a user by a meter or similar instrument

Other hypernyms of clock time include indication, reading.

clock time (noun)	meter reading (noun)
a reading of a point in time as given by a clock	the act of measuring with meters or similar instruments
	a datum about some physical state that is presented to a user by a meter or similar instrument