Discard vs Reverse
One answer
From the documentation:
http://publib.boulder.ibm.com/infocenter/clmhelp/v3r0/index.jsp?topic=/com.ibm.team.scm.doc/topics/t_reversing_change_set.html
Reversing: If you want to undo the delivery of a change set, you can create a change set that reverses all the changes in it and then deliver the reversed change set.
In other words, you're submitting a change set that undo's a change set -- and you can deliver this back to the stream to share this reversal.
http://publib.boulder.ibm.com/infocenter/clmhelp/v3r0/topic/com.ibm.team.scm.doc/topics/t_discarding_change_set.html
Discard: To remove a change set from your workspace, you can discard it. If you discard a change set from your workspace, you can also discard it from the stream the workspace flows to.
In other words, if you just want to *temporarily* remove a change set from your *workspace* you can discard it. It will not remove it from the stream nor will it share this with others.
http://publib.boulder.ibm.com/infocenter/clmhelp/v3r0/index.jsp?topic=/com.ibm.team.scm.doc/topics/t_reversing_change_set.html
Reversing: If you want to undo the delivery of a change set, you can create a change set that reverses all the changes in it and then deliver the reversed change set.
In other words, you're submitting a change set that undo's a change set -- and you can deliver this back to the stream to share this reversal.
http://publib.boulder.ibm.com/infocenter/clmhelp/v3r0/topic/com.ibm.team.scm.doc/topics/t_discarding_change_set.html
Discard: To remove a change set from your workspace, you can discard it. If you discard a change set from your workspace, you can also discard it from the stream the workspace flows to.
In other words, if you just want to *temporarily* remove a change set from your *workspace* you can discard it. It will not remove it from the stream nor will it share this with others.