Stack 2 Lists to Match

Hi, I have 2 lists that are both contain 3 columns worth of data. The first list is list A, the second is list B. See file below.

List A has more rows worth of data that list B. For every row of data in list B, there should be a match in List A. I simply need to rearrange list B so that it has its matching entry in list A. When this happens the "CHECK" column should be all zeros.

test.xlsx

thanks very much for this, I suppose I could just sort by Diff1 to get the matchup ... I sure wish I understood what you did so I can do it myself or would it take all day to explain lol?

thanks very much!