termination vs postfix

termination and postfix both are nouns.

Word	Noun	Adjective	Verb	Adverb
termination	Yes	No	No	No
postfix	Yes	No	No	No

As nouns, postfix is a hyponym of termination; that is, postfix is a word with a more specific, narrower meaning than termination:

termination: the end of a word (a suffix or inflectional ending or final morpheme)
postfix: an affix that is added at the end of the word

Other hyponyms of termination include suffix, inflectional ending, inflectional suffix.

termination (noun)	postfix (noun)
the act of ending something	an affix that is added at the end of the word
the end of a word (a suffix or inflectional ending or final morpheme)
something that results
a place where something ends or is complete
a coming to an end of a contract period