How to show the difference between 2 lines as Visual not tooltip !!

can you provide some sample data?

 

what is the order it should go in?  date?  how do you sequence these values?

 

in theor you need to;

1. create each line as a measure

2. then and substract line 1 - line 2 as another measure

3. plot the category on the x axis and the lines on the y axis as per your 

 

and then one frrom the other and plot it on the line chart.  you will need to play with the formatting a bit.