periodic event vs cycle

periodic event and cycle both are nouns.

Word	Noun	Adjective	Verb	Adverb
periodic event	Yes	No	No	No
cycle	Yes	No	Yes	No

As nouns, cycle is a hyponym of periodic event; that is, cycle is a word with a more specific, narrower meaning than periodic event:

Other hyponyms of periodic event include migration, oscillation, repeat, repetition, sunrise, sunset, beat, heartbeat, pulsation, pulse, tide.

periodic event (noun)	cycle (noun)
an event that recurs at intervals	a wheeled vehicle that has two wheels and is moved by foot pedals
	a single complete execution of a periodically repeated phenomenon
	a periodically repeated sequence of events
	a series of poems or songs on the same theme
	an interval during which a recurring sequence of events occurs
	the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)

periodic event (verb)	cycle (verb)
	recur in repeating sequences
	ride a motorcycle
	ride a bicycle
	pass through a cycle
	cause to go through a recurring sequence