In magration, animal travels in other places or it means they travel to other places where the weather is warmer or they can find food so they can live.

In hibernation, That is necessary because in winter many mammals wouldn't find food and if they wouldn't hibernate they would starve to death. Hibernation works by eating up what you could call an energy pack made of fats. One could say the fat also "protects" them from the ice cold winter.
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