What's the main difference between "rationality" and "reason?"

Native speaker’s answer
Rebecca
Although "reason" and "rationality" are often used interchangeably, reason refers to the human ability and can refer to a cause, while rationality is more technical and often refers to a relative standard to aspire to. Ex: What is the reason for the delay? Ex: He's irrational right now so don't bother reasoning with him. Ex: In difficult times, we must behave with common sense and rationality.