The broker represents the seller through a Residential Listing agreement; the buyer through a Buyer’s Representation agreement – in either case the broker is said to have “fiduciary” responsiblity towards the client. 

fi⋅du⋅ci⋅ar⋅y

/fɪˈduʃiˌɛri, -ˈdyu-/[fi-doo-shee-er-ee, –dyoo–] a person to whom property or power is entrusted for the benefit of another.

What a fiduciary owes to a principal (client):

• Obedience – to follow the lawful instruction of the client
• Loyalty – to act in the best interests of the client and loyal to the trust placed upon them
• Disclosure – the obligation to make full, fair, and timely disclosure to the client of all known facts relative or material to the transaction, whether favorable or unfavorable (e.g. the agent’s true opinion of a property; negotiating strategies; financial condition of the other party, etc. – these are not afforded to a “customer”, only a “client”).
• Confidentiality – the obligation to keep confidential any discussions, facts, or information about the principal (client) that should not be revealed to others (e.g. the client’s bargaining position; motivations for selling/buying; opinions of value; buyer’s highest price, etc. – these are not afforded to a “customer”, only a “client”).
• Accounting – keeping good records and insuring no commingling of funds (e.g. earnest money, etc.)
• Reasonable care and diligence – the agent is held to a standard of care that requires, among other things, that they be knowledgeable, concerning the land, the title, and the physical characteristics of the property being sold (e.g. guiding the buyer-client to accept a reasonable purchase price relative to market values; making available properties that meet the buyer’s purchasing objectives; investigating the material facts related to the transaction, etc.) – the agent is an “equity preserver” for the client.