Followers are people in your WNW orbit with varying degrees of acquaintance, from colleague to co-working space neighbor.
Vouching, on the other hand, is a level above this. When you vouch for someone you are saying that if you were unavailable, anyone you've vouched for would be a great replacement.
In order to vouch for a Creative, you both have to be Following one another. To Vouch for someone, click the "Vouch" button on the Action Bar. That person will be notified by email that you gave them your seal of approval.