wait vs hang on

wait is a noun but hang on is not a noun.

Word	Noun	Adjective	Verb	Adverb
wait	Yes	No	Yes	No
hang on	No	No	Yes	No

As verbs, hang on is a hyponym of wait; that is, hang on is a word with a more specific, narrower meaning than wait:

Other hyponyms of wait include expect, look forward, look to, hold on, hold the line, anticipate, look for, look to.

wait (noun)	hang on (noun)
the act of waiting (remaining inactive in one place while expecting something)
time during which some action is awaited

wait (verb)	hang on (verb)
look forward to the probable occurrence of	be persistent, refuse to stop
serve as a waiter or waitress in a restaurant	hold the phone line open
stay in one place and anticipate or expect something	fix to; attach
wait before acting