Comments/Notes are Shared by default, which will appear on the share back reports, and are posted to the Employee Portal if commenting is enabled.
Use the drop-down menu to switch the comment to Admin Only if you wish to have a private conversation with other admins to collaborate on the feedback, without employees seeing the dialog behind the scenes. Admin Only comments/notes only live on the admin dashboard and are only visible to other admins who can view the suggestion or response you are commenting/noting on. They do not appear on share back reports or in the Employee Portal. Read this article to learn more.