The two terms are in fact synonyms, even though the first is usually considered more violent than the other. Tornados generate the strongest winds that exist in the natural world. Wind speeds can exceed 500 km/hr and the upward currents can reach 300 km/hr.
The sign of a tornado on its way is a grey sky and a rumbling that sounds like a goods train coming. It is advisable to have a first aid kit to hand, with copies of your main documents attached. It is also advisable to turn off gas, electricity and water supplies. During the critical phase, take refuge if possible underground, preferably in a place without windows.
Keep away from any windows, and have a sleeping bag or blankets to offer protection from flying objects. If you are caught outside, leave your vehicle and try to take shelter in a safe place, stay lying down with your head covered or at least protected by your arms.