Active: An active volcano is basically a volcano that has erupted within the past 10,000 years. Dormant volcanoes are volcanoes that are expected to erupt again.

Extinct: Volcanoes that are considered extinct have not erupted since the last ice age. To simplify this, am extinct volcano is basically a volcano that hasn't erupted in ten thousand years and isn't expected to erupt again.

Active vs. Extinct