attachment vs fastening

attachment and fastening both are nouns.

Word	Noun	Adjective	Verb	Adverb
attachment	Yes	No	No	No
fastening	Yes	No	No	No

As nouns, attachment and fastening are synonyms defined as:

attachment (noun)	fastening (noun)
the act of fastening things together	the act of fastening things together
the act of attaching or affixing something	restraint that attaches to something or holds something in place
faithful support for a cause or political party or religion
a supplementary part or accessory
a connection that fastens things together
a writ authorizing the seizure of property that may be needed for the payment of a judgment in a judicial proceeding
a feeling of affection for a person or an institution