The asymmetry biomarkers are used to see if there is a lateralization of a biomarker. E.g they can be used to see if left frontal alpha activity is higher than right frontal alpha activity.
This figure shows the differences between the three asymmetry biomarkers given. If you do not understand any of this, please ask a tutor
If you are using the biomarker with channels then you should use the AsymBiomarker. If you are using regions then you should use the AsymRightbiomarker.