What's the difference between untwine and unwreathe?

Untwine

Definition:

• (v. t.) To untwist; to separate, as that which is twined or twisted; to disentangle; to untie.
• (v. i.) To become untwined.

Example Sentences:

• (1) Chromosomes partly untwine but remain attached at their kinetochores.

Unwreathe

Definition:

• (v. t.) To untwist, uncoil, or untwine, as anything wreathed.

Example Sentences: