attachment vs combining

attachment and combining both are nouns.

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

As nouns, combining is a hypernym of attachment; that is, combining is a word with a broader meaning than attachment:

Other hypernyms of attachment include combination, compounding.

attachment (noun)	combining (noun)
the act of fastening things together	the act of combining things to form a new whole
the act of attaching or affixing something	an occurrence that results in things being united
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