holdup vs armed robbery

holdup and armed robbery both are nouns.

Word	Noun	Adjective	Verb	Adverb
holdup	Yes	No	No	No
armed robbery	Yes	No	No	No

As nouns, holdup and armed robbery are synonyms defined as:

Other synonyms of holdup include heist, stickup.

holdup (noun)	armed robbery (noun)
robbery at gunpoint	robbery at gunpoint
the act of delaying; inactivity resulting in something being put off until a later time