What is the difference between the Brand and the Campaign versions?

You can add banners to the Brand version by adding the campaign to the signature design.
And use the campaign features with the ‘Powered by Xink’ footer; 

1. Scheduling, 
2. Segmentation and 
3. Tracking email signature campaigns.

The Campaign version includes the Brand version and removes “Powered by Xink” when using the Campaign menu.