Difference in Ladybug radiation on same facade when analyzed in two ways

Why is the solar radiation different for the same facade(side of the building) when I first run the radiation analysis on the whole building and then only on the facade surface?
The value for the same facade is 83.87 kWh/sqm and 20.76kWh/sqm respectively.

If you carefully look at the Legend, you will see that the Minimum & Maximum Values Differ between the two analyses. since Ladybug take your results and assign color gradient to the mesh representing these results.

To fix this issue you need to connect Ladybug Legend Parameters, and assign Minimum & maximum values, Example Minimum =0 , Maximum = 100, the color gradient will match.