You can create as many roles as you like.
Roles with edit permissions on a page are equivalent to publishers on that page. Anyone in roles with edit permissions will get the workflow notifications.
Roles with draft edit permissions are authors and can submit.
Content Administrator role is special, a user in this role can edit any content anywhere in the site.
So you could create a section of the site for marketing and create a marketing publishers role which has edit permissions on all pages in that section. Then you could create a marketing authors role and give that role draft edit permissions.
Now marketing authors can edit drafts and submit to marketing publishers.
The included roles "Content Authors" and "Content Publishers" are not special, they are just for illustrative purposes, you can delete those roles and make your own. There are only a few special roles and the special roles cannot be deleted.
Hope it helps,