There simply are different permission group ("role") definitions for the site context vs. the global context. The "Manager" is what a "Coordinator" would be in the global context. A "Editor" role simply does not exist in a site context, as it was deemed unnecessary for a context aimed at collaboration in the style of a SharePoint workspace / site.
Technically speaking though, all the global context roles are also "available" within the site context, they are merely not shown in the UI to avoid (more) confusion when similarly named roles would are present. Furthermore, the "Collaborator" role in sites is not even named "Collaborator", but "SiteCollaborator" - same for the other site context roles - and the label used in the UI is another simplification.