4 Wheel Drive/SUVs: What is the difference between 4-wheel and AWD?, gas mileage, snowy conditions

Question
Which is better in snow, 4-wheel drive or AWD?  And which allows for better gas mileage, which is harder on tires?  Does a manual transmission allow for better control in snowy conditions or is that a myth? Regarding repair bills and/or general maintenance, is a manual transmission better, equal or worse than an automatic transmission?  The answers to the above questions will give me a better idea of what new car/SUV to pick out for driving at high altitude on snowy, winding roads.  Reliability and safety are my main concerns.  Thank you.  

Answer
Thanks Carol for a great question, but since I live in Florida I am not really aware of snowy conditions.  AWD means that all four wheels are in gear at all times.  4WD means that you have the capability of having either the rear two wheels, or all four being driven.  As to the transmission question the new automatics are so good that they perform as well, if not better, than the manuals and one thing to consider is that trade-in value for a vehicle with a manual transmission is not nearly as good as for an automatic.  A lot of people have no idea how to drive a manual.  Again, thanks for the question and best of luck.  Bud