on Writing Forward:

The premise of a story can be summed up in a few words: imagine a world in which robots have taken more than half of all jobs. A premise sets the stage and gives us a vague idea of what a story is about, but it doesn’t tell us the specifics. Concepts get into specifics.

There are two kinds of concepts: high and low. A low concept is stripped down and generic: a man loses his job to a robot. A high concept adds interest and details that inspire interest in a story: When half of the population finds itself jobless as a result of automation, one man raises a rebellion to seize resources essential to survival.

Note the key differences between premises and concepts: Premises paint a vague picture of a story world and situation. Concepts identify key points, such a protagonist, an antagonist, a setting, and a central story question or problem (plot).