Compare values from two columns

To compare strings from 2 differents column and present the results in a third one, use the following expression:

if(cells["a"].value == cells["b"].value, "Y", "N")

You can facet Y and N on the third column to see which strings are similar or not.

An other option is to do this straight from the facet (so you do not have to create an other column and the filter on it). To do so, use custom text facet and key the following expression:

value == cells["b"].value