Check the T option located in the bottom of the panel to change the font to fixed width.
This font makes it easier to see the difference between the different members of the cluster.
The additions operation highlights the characters added (that are different) to the Change to Value.
For example if New York City is the Change to Value and Noo York City is a member of the cluster when we perform the cluster and edit operation, the additions operation will highlight the words oo as that is the differentiator between the Change to Value and the member of the cluster.
The deletions operation higlights the character positions where there occurs a difference between the Change to Value and the member of the cluster.
Now consider the same example used above, the Noo York City value in the cluster would appear as New York City with ew striked out (See Image Below). The font strikethrough effect on the Letters ew tells us that a difference exists in those two characters between the cluster head and the value falling under the cluster.