Name 2 ways to tell the difference between atrial tachycardia and atrial flutter

Superficially atrial tachycardia can resemble atrial flutter. However in atrial tachycardia the baseline between P waves is isoelectric unlike flutter where there is a sawtooth pattern and the rate is generally slower, in the range of 100-250 beats/min, relative to flutter which is generally 250-350 beats/min.

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Source

Goldberger: Clinical Electrocardiography: A Simplified Approach, 7th ed.