The Difference between Collaborators and Team Members
Team Members are users that are added to your Team, they can create new projects, share files and can invite users to projects on your team.
A Collaborator is a user you can invite into an individual project, they will not have access to, or any visibility into other projects on your team.
Adding users to your project as a Collaborator
To add a Collaborator to a project, open the project and click “+” in the top right corner. Click Add Individual People and type in his or her email address and invite them to the project.