Difference between Inexpugnable and Impregnable

What is the difference between Inexpugnable and Impregnable?

Inexpugnable as an adjective is impossible to eliminate or destroy; impregnable while Impregnable as an adjective is (of a fortress, wall, etc.) too strong to be penetrated.

We hope you now know whether to use Inexpugnable or Impregnable in your sentence.