join vs attach

join is a noun but attach is not a noun.

Word	Noun	Adjective	Verb	Adverb
join	Yes	No	Yes	No
attach	No	No	Yes	No

As verbs, attach is a hyponym of join; that is, attach is a word with a more specific, narrower meaning than join:

join (noun)	attach (noun)
a set containing all and only the members of two or more given sets
the shape or manner in which things come together and a connection is made

join (verb)	attach (verb)
make contact or come together	become attached
cause to become joined or linked	cause to be attached
become part of; become a member of a group or organization	be attached; be in contact with
come into the company of	take temporary possession of as a security, by legal authority
be or become joined or united or linked	create social or emotional ties