Pacify, appease, placate, mollify, propitiate, conciliate are comparable when they mean to quiet excited, aroused, or disturbed persons.
Pacify implies a soothing or calming of anger, grievance, or agitation, or the quelling of insurrection especially by force.
Appease may indicate the quieting of agitation or insistent demand by the making of concessions and it may be used in reference to appetites, desires, and passions as well as persons and to imply a giving of quietening satisfaction.
Placate is sometimes interchangeable with appease but may imply a more complete or lasting assuagement of bitter feeling.
Mollify stresses softening of anger or abatement of hurt feelings by positive action (as flattery or concession).
Propitiate may refer to averting the anger or malevolence or winning the favor of a superior or of one possessing the power to injure greatly.
Conciliate may be used of situations in which an estrangement or dispute is settled by arbitration or compromise.