permutation vs substitution

permutation and substitution both are nouns.

Word	Noun	Adjective	Verb	Adverb
permutation	Yes	No	No	No
substitution	Yes	No	No	No

As nouns, permutation and substitution are synonyms defined as:

permutation and substitution: an event in which one thing is substituted for another

Other synonyms of permutation include replacement, switch, transposition.

permutation (noun)	substitution (noun)
complete change in character or condition	the act of putting one thing or person in the place of another:
the act of changing the arrangement of a given number of elements	an event in which one thing is substituted for another
act of changing the lineal order of objects in a group
an event in which one thing is substituted for another