Comparing data sets

Hi Anonymous ,

We can create a measure and use it in condition format to meet your requirement.
1. create a measure that calculate the difference of the [ABV] column in the same forecasted month.

Measure = 
var LastExactDate = 
CALCULATE(
    Max('collated_Table'[Exacted_Date]),
    FILTER(
        ALLSELECTED('collated_Table'),
        collated_Table[Exacted_Date]<MIN('collated_Table'[Exacted_Date])&&'collated_Table'[Forecasted_Month] in DISTINCT('collated_Table'[Forecasted_Month])
        )
    )
var LastABV = 
CALCULATE(
    SUM('collated_Table'[ABV]),
    FILTER(
        ALLSELECTED(collated_Table),
        'collated_Table'[Exacted_Date]=LastExactDate&&'collated_Table'[Forecasted_Month] in DISTINCT('collated_Table'[Forecasted_Month])
        )
    )
return 
SUM(collated_Table[ABV]) – LastABV

2. apply icon condition format with [ABV], and use measure in ‘Based on field’ 

3. Then we can get the result like this,

If it doesn't meet your requirement, Could you please show the exact expected result based on the Tables that you have shared？