What is the difference between a Co-Performer and a Collaborator?

Both are individuals who appear in your content.
Co-Performers are added by manually submitting IDs and Release Forms in the Co-Performers tab of your Core Settings. They may or may not be a verified member of the Model Program If they are a Model, it’s possible that they haven’t opted into Collaborators yet.
A Collaborator is a verified member of the Model Program whose IDs have already been verified in our database and has opted into the tagging system. By approving a Collaboration request, you grant your Collaborator permission to upload content you appear in. Because you are already a verified Model, they can upload and tag you in content without having to submit your ID and Signed Agreement.