fashion vs manner

fashion and manner both are nouns.

Word	Noun	Adjective	Verb	Adverb
fashion	Yes	No	Yes	No
manner	Yes	No	No	No

As nouns, fashion and manner are synonyms defined as:

Other synonyms of fashion include mode, style, way.

fashion (noun)	manner (noun)
characteristic or habitual practice	a way of acting or behaving
consumer goods (especially clothing) in the current mode	how something is done or how it happens
how something is done or how it happens	a kind
the latest and most admired style in clothes and cosmetics and behavior

fashion (verb)	manner (verb)
make out of components (often in an improvising manner)