Is a sinus tachycardia the same thing as supraventricular tachycardia?

Depends. Depends on how fast or how slow, the cause for the abnormal rate and whether or not it is causing any symptoms. Both abnormally slow and fast heart beats can cause congestive heart failure and syncope (fainting). Persistent fast heart beats can cause weakness of heart muscle referred to as tachycardia induced cardiomyopathy.