Note that both the versions are licensed per developer. Here are the differences between the 2 versions:

The Regular Edition provides you the following:

  1. Includes 1 Year of Subscription.
  2. Unlimited Support (2 day response time) while Subscribed.
  3. Access to all Official releases while Subscribed.

The Enterprise (or Source) Edition provides you the following:

  • Includes 1 Year of Subscription.
  • Full unminified, debuggable Source for our Gantt Widgets.
  • Priority, Unlimited Support (1 day response time) while Subscribed.
  • Access to all Official and unofficial releases while Subscribed.