Atlassian Forge Apps are a new class of apps designed only for Atlassian Cloud.
Unlike Atlassian Connect apps which are based on external micro-services, Forge apps are hosted and executed inside Atlassian Cloud.
The key benefits of Forge Apps are:
Data Residency ready- The app data resides in Atlassian Cloud, making it easier to comply with GDPR and other regulatory requirements
Fast - All the computation is done within the same infrastructure as Confluence or Jira