When using CrossEngage, you have the option to either use Audience or Realtime Campaigns.
An Audience Campaign is a campaign that is set to go out at a specific time and is only performed on a segment of users. This means that you are segmenting for certain traits such as gender or country. It is possible to take user behaviour into account when segmenting, by looking for the event count of a user.
When it comes to user behaviour, an Audience Campaign always asks What has the user done up to this point?
A Realtime Campaign is performed on a user segment and a user journey. This means that on top of all the possibilities of segmentation that you have available in an Audience Campaign, you also have the ability to set a chain of user behaviour events that should trigger a campaign.
When it comes to user behaviour, a Realtime Campaign always asks What will the user do in the future that I want to react to in Realtime?