This module was tested on 5th December 2018, Drupal 8.6.4 with Acquia Cohesion 5.2 using version 8.x-1.0-rc2 of the module.
You can not set the Layout Canvas field to be compared in the Diff module settings. If your content types have other fields attached, those can still be compared as expected.
Link to the module
The module can be found on Drupal.org here.
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