The description of what a Difference merge will do is confusing. It says "Remove items in chosen list" -- that makes it seem like it will leave the result in the current list that you clicked the Merge menu from, when actually it does the safer thing, which is to create a new PL with the result. Please change the wording somehow to convey this and reassure people. I was wanting to request an option to create a new list with the results rather than affect my current list, but then after trying it I realized that's already what it does.
I would suggest better wording might be: "Items in current but not chosen list." The wording "current" vs. "chosen" might not be 100% understandable; however that could be rectified by adding a line of text at the top of the merge menu saying "Current list: Name of current list."
