They most often form in association with severe thunderstorms which develop in the high wind-shear environment of the Central Plains during spring and early summer, when the large-scale wind flow provides favorable conditions for the sometimes violent clash between the moist warm air from the Gulf of Mexico with the cold dry continental air coming from the northwest.
However, tornadoes can form in many different circumstances and places around the globe.
Hurricane landfalls are often accompanied by multiple tornadoes.
Hurricanes, on the other hand, are large-scale circulations with horizontal dimensions from 60 to well over 1000 miles in diameter.
They form at low latitudes, generally between 5 and 20 degrees, but never right at the equator.