How to compare 2 rows of data and show the result in 3rd rows?

I trying to calculate difference between 2 rows, e/g:

Row1: 1, "Brazil", 3, 4, 5  Row2: 2, "Brazil", 5, 6, 6  Row3: 1, "Brazil", 2, 2, 1  

The first and sec row was group by result from different table, and i need the third row the show the different. i tried the inner join on same table method, but it does not behave like i wish. does anyone have idea on this ?

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