retardation vs time lag

retardation and time lag both are nouns.

Word	Noun	Adjective	Verb	Adverb
retardation	Yes	No	No	No
time lag	Yes	No	No	No

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

Other hypernyms of retardation include delay, hold, postponement, wait.

retardation (noun)	time lag (noun)
the act of slowing down or falling behind	time during which some action is awaited
a decrease in rate of change
lack of normal development of intellectual capacities
any agent that retards or delays or hinders
the extent to which something is delayed or held back