retirement plan vs IRA

retirement plan and IRA both are nouns.

Word	Noun	Adjective	Verb	Adverb
retirement plan	Yes	No	No	No
IRA	Yes	No	No	No

As nouns, IRA is a hyponym of retirement plan; that is, IRA is a word with a more specific, narrower meaning than retirement plan:

retirement plan: a plan for setting aside money to be spent after retirement
IRA: a retirement plan that allows you to contribute a limited yearly sum toward your retirement; taxes on the interest earned in the account are deferred

Other hyponyms of retirement plan include 401-k, 401-k plan, individual retirement account, Keogh plan.

retirement plan (noun)	IRA (noun)
a plan for setting aside money to be spent after retirement	a retirement plan that allows you to contribute a limited yearly sum toward your retirement; taxes on the interest earned in the account are deferred
	a militant organization of Irish nationalists who used terrorism and guerilla warfare in an effort to drive British forces from Northern Ireland and achieve a united independent Ireland