ninjutsu vs ninjitsu

ninjutsu and ninjitsu both are nouns.

Word	Noun	Adjective	Verb	Adverb
ninjutsu	Yes	No	No	No
ninjitsu	Yes	No	No	No

As nouns, ninjutsu and ninjitsu are synonyms defined as:

ninjutsu and ninjitsu: the traditional Japanese method of espionage; involves stealthy movements and the use of camouflage

ninjutsu (noun)	ninjitsu (noun)
the traditional Japanese method of espionage; involves stealthy movements and the use of camouflage	the traditional Japanese method of espionage; involves stealthy movements and the use of camouflage