rush vs flash

rush and flash both are nouns.

Word	Noun	Adjective	Verb	Adverb
rush	Yes	Yes	Yes	No
flash	Yes	Yes	Yes	No

As verbs, flash is a hyponym of rush; that is, flash is a word with a more specific, narrower meaning than rush:

Other hyponyms of rush include barge, push forward, thrust ahead, buck, charge, shoot, shoot down, tear, dart, dash, scoot, scud, shoot.

rush (noun)	flash (noun)
the act of moving hurriedly and in a careless manner	a lamp for providing momentary light to take a photograph
(American football) an attempt to advance the ball by running into the line	a bright patch of color used for decoration or identification
a sudden forceful flow	a momentary brightness
a sudden burst of activity	a sudden brilliant understanding
the swift release of a store of affective force	a short news announcement concerning some on-going news story
grasslike plants growing in wet places and having cylindrical often hollow stems	a burst of light used to communicate or illuminate
	a gaudy outward display
	a sudden intense burst of radiant energy
	a short vivid experience
	a very short time (as the time it takes the eye to blink or the heart to beat)

rush (adjective)	flash (adjective)
done under pressure	tastelessly showy
not accepting reservations

rush (verb)	flash (verb)
act at high speed	appear briefly
urge to an unnatural speed	emit a brief burst of light
attack suddenly	make known or cause to appear with great speed
cause to occur rapidly	protect by covering with a thin sheet of metal
move hurridly	run or move very quickly or hastily
run with the ball, in football	gleam or glow intermittently
cause to move fast or to rush or race	display proudly; act ostentatiously or pretentiously
	expose or show briefly