mnemotechnic vs mnemonic

mnemotechnic is not a noun while mnemonic is a noun.

Word	Noun	Adjective	Verb	Adverb
mnemotechnic	No	Yes	No	No
mnemonic	Yes	Yes	No	No

As adjectives, mnemotechnic and mnemonic are synonyms defined as:

mnemotechnic and mnemonic: of or relating to or involved the practice of aiding the memory

Other synonyms of mnemotechnic include mnemotechnical.

mnemotechnic (noun)	mnemonic (noun)
	a device (such as a rhyme or acronym) used to aid recall

mnemotechnic (adjective)	mnemonic (adjective)
of or relating to or involved the practice of aiding the memory	of or relating to or involved the practice of aiding the memory