Duress involves threats and coercion while undue influence involves persuasion to susceptible individuals.

Duress

A situation where a person is forced to perform an act against their will or face threats, violence, constraints, or other action upon their person or property, which is used as a means to compel their agreement or action.

Undue Influence

A situation where an individual is able to influence another person's decisions due to a special relationship, often leading to unfair advantages.