This tool is based on UNIX shell command comm. It compares two datasets and returns similarities or differences. For example, if you have two datasets:

a  1
b  2
c  3

and:

a  1
f  6
h  8

Using this tool with Lines unique to Dataset1 option will return:

b  2
c  3

If you use Lines shared between Dataset1 and Dataset2 option output will look like this:

a  1