activity vs overdrive

activity and overdrive both are nouns.

Word	Noun	Adjective	Verb	Adverb
activity	Yes	No	No	No
overdrive	Yes	No	Yes	No

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

activity: the state of being active
overdrive: the state of high or excessive activity or productivity or concentration

Other hyponyms of activity include agency, busyness, hum, behavior, behaviour, eructation, eruption, extravasation, operation, play, swing.

activity (noun)	overdrive (noun)
any specific behavior	a high gear used at high speeds to maintain the driving speed with less output power
the trait of being active; moving or acting rapidly and energetically	the state of high or excessive activity or productivity or concentration
an organic process that takes place in the body
a process existing in or produced by nature (rather than by the intent of human beings)
the state of being active
(chemistry) the capacity of a substance to take part in a chemical reaction

activity (verb)	overdrive (verb)
	make use of too often or too extensively
	drive or work too hard