If benzos & alcohol have same function then why do i feel much better in terms of calmness/positive thinking after drinking alcohol than taking any dose of benzos? if alcohol & benzos are same then why alcohol is freely available but benzos r not?

Alcohol has been around for too many years to do much about it and has ruined the health of many millions of people in the world. If you're drinking alcohol in order to keep calm or positive in attitude, dangerous dependency is a real threat. It's actually a depressant. One drink a day could be enjoyable & reasonable. Benzodiazepines(tranquilizers) can also be abused but at least are regulated.

Benzos and alcohol are totally different chemicals, only some of their effects overlap as far the central nervous system. Everything else has to do with individual tolerance and sensitivity, both can cause acute and chronic life threatening complications.