spark vs occur

spark is a noun but occur is not a noun.

Word	Noun	Adjective	Verb	Adverb
spark	Yes	No	Yes	No
occur	No	No	Yes	No

spark (noun)	occur (noun)
merriment expressed by a brightness or gleam or animation of countenance
a momentary flash of light
a small fragment of a burning substance thrown out by burning material or by friction
electrical conduction through a gas in an applied electric field
a small but noticeable trace of some quality that might become stronger

spark (verb)	occur (verb)
put in motion or move to act	come to pass
emit or produce sparks	come to one's mind; suggest itself
	to be found to exist