Time Intelligence DTD

HI Pentanol

Andrew

Try this solution

First Add a calculated Column which will RANK the dates for each SKU

Date RANK =
RANKX (
    FILTER ( ALL ( Table1 ), Table1[SKU] = EARLIER ( Table1[SKU] ) ),
    Table1[Date],
    ,
    ASC,
    DENSE
)

Now you can get the Change in Difference using this Calculated Column

Change_In_Difference =
VAR previousDayDifference =
    CALCULATE (
        SUM ( Table1[Comp Price] ) - SUM ( Table1[Our Price] ),
        FILTER (
            ALLEXCEPT ( Table1, Table1[SKU] ),
            Table1[Date RANK]
                = EARLIER ( Table1[Date RANK] ) - 1
        )
    )
VAR CurrentDayDifference = Table1[Comp Price] - Table1[Our Price]
RETURN
    CurrentDayDifference - previousdayDifference

Pentanol

See the pic below.I just added another SKU to your sample data