title: Discrepancy between layer digests obtained with `docker inspect` and those from the registry API
body: <p><code>docker inspect --type image the_image</code> on a local image yields a list of SHA256 digests (<code>RootFS/Digests</code>) which isn't the same as the one I get from the same image in the registry (<code>ManifetsV2/Layers/*/Digest</code>).</p>
  
  <ul>
  <li>Docker is 18.03.1-ce</li>
  <li>Registry is "github.com/docker/distribution v2.6.2"</li>
  </ul>
  
  <p>Is this discrepancy normal? If so is there a way to match layers in a local image with layers in a registry image without pulling the registry image?</p>