Difference between Wyvern and Wivern

What is the difference between Wyvern and Wivern?

Wyvern as a noun is mythical dragon-like creature, having wings, only two legs and a barbed tail. while Wivern as a noun is a draconian creature possessing wings, only two legs and usually a barbed tail.

We hope you now know whether to use Wyvern or Wivern in your sentence.