Typical use case for worktree(s) is to work on feature/hotfix branch without touching the current master/wip branch.

So, in the context of worktrees I read _"The way we're doing it, the branches are both in the same working directory at the same time"_ as having both the branch's files (not changes) available in the same worktree.

Thanks for clarifying that it is similar to changelists.