If u have ectopic atrial tachycardia, does the ectopic signal cause the ventricles to beat too? and what's the difference with reentry tachycardia?

EAT: Atrial tachycardia, regardless of mechanism, conducts to the ventricles. The main issue with any form of atrial tachycardia is that the rapid ventricular rate can result in annoying symptoms and, if fast and persistent, can eventually weaken the heart. The difference between EAT and reentry is one of mechanism. (ie how the electrical impulse is conducted). Incessant EAT requires treatment.