What is the difference between AF and atrial flutter?

Atrial flutter occurs when a “reentrant” circuit is present, causing a repeated loop of electrical activity to depolarize the atrium at a rate of about 250 to 350 beats per minute ; the atrial rate in atrial fibrillation is 400 to 600 bpm.

This is because the P waves (flutter waves ) in atrial flutter occur at about 250-350 per minute (usually around 300). At this rate, it can appear that there is a P wave in front of each QRS and a T wave after each QRS.15 Kas 2016

In atrial fibrillation, the atria beat irregularly. In atrial flutter, the atria beat regularly, but faster than usual and more often than the ventricles , so you may have four atrial beats to every one ventricular beat.