The difference between them is as below: if you look at the properties for each label
and
In the first image the whole label is white-out background. In the second the font/text itself has a white-out background. Now there are script commands to apply italics, superscripts, underline etc to the text but I can't find any to apply the whiteout to the background. I don't really want to do this manually all the time and the text needs to align itself with an angled line so the full label white-out is not ideal.
I am sorry that we cannot control this option via LabTalk so far, but I will forward your issue to our share meeting to see if we could improve it in the future.