HighTower Advisors has created a great video comparing investment brokers with fiduciaries.
A broker  is someone who takes a fee in exchange for executing a transaction. They provide a service in return for compensation. For the most part, a broker is not a fiduciary. However, brokers – depending on where they reside, professional qualifications, company, regulatory oversight, etc. – may have certain duties of care to their clients.
It is an important distinction. Make certain that you always know whether you are dealing with a fiduciary or not. I am not saying never to deal with a non-fiduciary. Only that you know the difference between the two. And, if appropriate, take steps to safeguard your best interests over those of your representative (agent, banker, broker, financial planner, etc.).
Now to the HighTower video.
Butcher Versus Dietician
In the video, the broker is a meat butcher. The butcher knows meats and if you want meat will (hopefully) sell you the best meat for your needs. I say hopefully as there must be elements of competence and honesty in the butcher. Not to mention trust between the customer and vendor. If any of those are missing, major problems can arise. The butcher is not going to sell you fruits or vegetables. Nor tell you that you should cut back on your intake of red meat for health reasons.
The fiduciary is more a dietician. A dietician should take a holistic view of your life based on your unique situation (using an Investor Profile  and Investment Policy Statement ). Then provide the best recommendations for you. Not what the dietician prefers for him/herself, or based upon what is in his/her best interest to sell. Only what is right for your specific needs.
As the video nicely states:
“Broker are butchers selling you product. Fiduciaries are dieticians looking after your health.”
“The problem is most people think their butcher is a dietician.”
The world needs both butchers and dieticians. As well as brokers and fiduciaries.
Use each in their place and do not confuse the two. Otherwise, it will end badly.