To be clear, the tax code establishes IRAs as being either Individual Retirement Accounts under § 408(a) and CFR § 1.408-2 or as Individual Retirement Annuities under § 408(b) and CFR § 1.408-3. But yes, you can think of an Individual Retirement Annuity as being an annuity held within an Individual Retirement Account since both are subject to essentially the same rules. Whether or not the particular annuity in question is an IRA depends on how the account was established and maintained, not by whether or not the annuity is compatible with an IRA.
