The main difference between local and general anesthetics is how much area of the body is affected. Local anesthetics only affect one part of the body such as your skin, teeth and gums, or even the spinal cord. General anesthetics affect the whole body.
There is a difference between a loss of consciousness from a general anesthetics and a deep sleep, although they are similar. In a dream, the brain forms dreams and processes information. However, the loss of consciousness does not create dreams, or even store memories.
An anesthetic is called an inhalant when it is administered through the lungs.
Nitrous oxide can cause the lungs to collapse and lower oxygen levels in tissues, so it is not used as much anymore as in the past.
Diethyl ether isn't used as much anymore either because it is very flammable, especially in the presents of oxygen, and was a fire hazard during surgeries.
Anesthetics work by preventing the nerve's communication to the brain. When this connection is interrupted, no pain can be felt. They prevent the sodium ions from getting from one nerve to the next.
