A fiduciary standard is stricter than a suitability standard. Suitability asks whether a recommendation is appropriate; a fiduciary standard asks whether it is the best available option known to the adviser, and requires disclosure or avoidance of conflicts such as commissions and proprietary product sales.
Which standard applies depends on the regulatory hat the person wears, not on their job title. The same individual can be a fiduciary on advisory accounts and subject to a lesser standard on brokerage accounts in the same meeting.
Practical checks: ask for the duty in writing, ask how the person is paid by anyone other than the client, and ask whether a cheaper share class of any recommended fund exists. See twelve-b-one-fee and soft-dollars.
Related: soft-dollars, twelve-b-one-fee, wrap-fee, investment-policy-statement, sec, performance-reporting