Drop Date field and dimension and measure to find the difference.
Use the Add quick calculation to find the difference across the table.
Right click on your measure field and Go to Add quick calculation and select Difference.
If you want to show vertical difference then right click on the field and go to Compute using and change to the table (down).
To convert into % drop the same measure again and follow the same above steps,
Go to Edit quick calculation and select the calculation type as the percent difference from and select ok.
Hope it helps.