What is the difference between getting high( i.e. using alcohol or similar things) and getting unconcious using general anesthesia? I  searched the internet about the difference but couldnt really understand it.I am not asking about the difference in the type of drugs used, Iam interested in the difference in the state of unconciousness.(Iam not sure whether "getting high" can be called unconcious.)
The short answer to what the difference between getting high and getting unconscious using general anaesthesia - It simply boils down to a matter of dosage levels and medical supervision!

And now to clarify ...

When you are put under general anaesthetic the attending anaesthesiologist will be administering possibly multiple drugs that work together to achieve the required effect of preventing you from moving your body, and your brain from being aware of whats happening to your body.
   The precise dosages and the timing of there administration are carefully chosen to ensure you stay blissfully unaware and immobile for the duration of the procedure.

Now compare that to you going out for a night on the town where ideally the only one administering any drugs is you (for better or worse) - barring any accidental overdoses from you pounding down a full bottle of spirits in one turn - the dosages you put in your system are thankfully just not in the same league as what you would receive on the operating table and so you just get high or obnoxious as apposed to getting into what is technically a medically induced coma.

One of the major characteristics of that induced coma is that your body looses its protective reflexes and your at the mercy of the attending medical teem to prevent you from choking on your own tongue - when you hear of someone outside of a hospital dying from an overdose whether it be drug or alcohol, a lot of the time the cause of death isn't the toxicity but that same loss of protective reflexes that doesn't save them as they asphyxiate on there own tongue or vomit after slipping into a deep sleep (or coma).