Is there a difference between vent rate from an ecg and pulse rate from a pulse ox or are they essentially the same number?

The ventricular rate from an EKG is more accurate than pulse rate from a pulse ox in case of arrhythmia. If patient is in normal sinus rhythm and there is no problem with peripheral perfusion (normal blood pressure and cardiac output), both rates are the same.

The ventricular rate from an ECG is the actual number of electrical signal from the heart. The pulse rate from a pulse oximeter detects the pulse rate from the finger or whatever site the oximeter is attached to. In most situations these are the same. However during some arrhythmias, not every ECG waveform results in a cardiac contraction that is detected by feeling the artery.