Board Thread:General Discussion/@comment-25326704-20180710022514/@comment-1038387-20180710122242

The distinction between Vertigo and DC didn't come until Brightest Day, when John Constantine walked in fresh from the pages of Swamp Thing (rather than pushing 70 like in Hellblazer). We didn't bother to retroactively change anything else, especially because the border is hazy.

references events from both and  (Gabriel's treatment), so they take place in that same Not-quite-New-Earth-but-Vertigo-Universe.