Paul Ekman: States of Emotion Moods, Traits, and Disorders

The following is a look at some main points from “The Nature Of Emotion“, by Dr. Ekman on the difference between mood and emotion.
An easy way to understand the difference between moods and emotions is to consider moods can last for hours while emotions last only a few seconds. For this reason it’s easier to identify emotional triggers but difficult to figure out why someone is experiencing a certain mood.
Facial expressions are also unique to emotions while you don’t generally see a person’s facial expression change much from a mood.

Moods can be distinguished from emotions in terms of their duration. There’s no consensus on how long an emotion can last but researchers of mood and emotion recognize moods last longer.
An extended emotion lasting hours is likely a series of recurring emotional episodes. Moods, however, can last for hours, days, weeks or longer.
Moods also leave the provocation of emotions easier to obtain. For that reason, for instance, if a person is irritated, it will be much easier for them to be angered. An angry response is even a way to indulge in the emotion of irritation.
A person dealing with a mood isn’t provoked as easily as someone dealing with an emotion. Also, a person in the middle of an emotional response will find it more difficult to recover from an emotion such as anger. The emotion will likely last longer than a person dealing with a mood who is provoked.
Facial expressions are also much different between moods and emotions. A person dealing with a particular mood, depression, anxiety, euphoria, may not look much different than if they were feeling bored or tired. Meanwhile, a person dealing with a particular emotion will likely exhibit recognizable facial expressions such as anger or fear.
Being able to identify triggers is also a difference between mood and emotions. A person dealing with a certain mood isn’t likely to be able to specifically tell how they ended up feeling the way they do. They can probably piece together a series of events, but cannot pinpoint one exact moment or experience.
A person dealing with an emotion generally can isolate the contributing factor to why they were angered, fearful, joyous, agitated, etc.
This type of revelation, however, generally comes after a period of time later when reflecting on the emotional response to something.