ECApplicationException : This EXCEPTION is thrown if the error is related to user input and will always fail. For example, when a user enters an invalid parameter, an ECApplicationException is thrown. When this exception is thrown, the solution controller does not retry the COMMAND, even if it is specified as a retriable command.

ECSystemException : This exception is thrown if a RUNTIME exception or a WEBSPHERE Commerce configuration error is detected. Examples of this type of exception include create exceptions, REMOTE exceptions, and other EJB exceptions. When this type of exception is thrown, the solution controller retries the command if the command is retriable and the exception was caused by either a database deadlock or database rollback. 

ECApplicationException : This exception is thrown if the error is related to user input and will always fail. For example, when a user enters an invalid parameter, an ECApplicationException is thrown. When this exception is thrown, the solution controller does not retry the command, even if it is specified as a retriable command.

ECSystemException : This exception is thrown if a runtime exception or a WebSphere Commerce configuration error is detected. Examples of this type of exception include create exceptions, remote exceptions, and other EJB exceptions. When this type of exception is thrown, the solution controller retries the command if the command is retriable and the exception was caused by either a database deadlock or database rollback.