The difference command removes all keys from the destination which are present in the source, and leaves all others alone.

The symmetric difference command removes all keys from the destination which are present in the source, and adds all keys from the source which are not present in the destination.

Additionally the into clause has been added to all array set set operations (union, intersect, difference, symmetric difference) allowing commands such as:

intersect tLeft with tRight into tResult

The operation of the commands is the same as the non-into form except that tLeft does not have to be a variable, and the result of the operation is placed into tResult rather than mutating tLeft.