An agent is a user in your helpdesk who takes care of the support activities as a full-time job. An agent can be assigned the role of an admin, supervisor or given a custom role with specified duties. 

However, a collaborator is a third-party member you invite to be part of a support ticket. These collaborators are not part of your helpdesk but can be added to specific tickets as a one-time activity. 

A few scenarios where you can add collaborators are to provide approvals on a refund request, provide insights on a business use case or give information related to resolving the ticket.

Admins can invite Collaborators from outside the team to your Freshdesk account to collaborate on tickets or give your agents the privilege to invite collaborators.

Collaborators will then receive an email inviting them to log into their Freshdesk account. They can then view the ticket and customer details and collaborate by responding to the private note and helping full-time agents resolve the ticket faster.