Collaboration allows you to solicit feedback from stakeholders about your survey. Its a simple way to send out a link to your boss/colleague and see what they think of the survey. Draft / Collaborate mode allows peers to give you real-time feedback on your survey as they are taking / reviewing it. Users can provide comments on a question-by-question basis and reviewers can see each others comments.
The advantage is that collaborators can also make minor modifications to the survey (like correct spelling errors, etc.) directly as they are taking the survey. All changes are logged for auditing purposes.
