Decision 

A Decision allows one of several possible paths to execute, based on expression logic. This element is used to create complex expressions that determine the path of the Business Process . It also contains the expression and connection names. 

Decisions allow you to define expressions that are evaluated to determine the proper Business Process flow. Expressions are built using the mapping interface and Business Process attributes. 

Event Based Decision 

Multiple possible messages can be juxtaposed against a timeout condition to allow the type of message received to determine the appropriate Business Process path. 

Flow 

Allows you to specify one or more activities to be performed concurrently.