This seems to work

Private Sub Worksheet_Activate()
Dim c, x As Range

For Each c In ActiveSheet.UsedRange
If Not c = "" Then
Set x = Worksheets(1).UsedRange.Find(c.Value)
If Not x Is Nothing Then
c.Interior.Color = RGB(0, 255, 255)
End If
End If
Next c
End Sub

I am concerned that is there are a lot of numbers  in each sheet  it may be
slow.
It works when the second sheet is activated. i.e. when you switch to it.

If you have both sheets  showing in two windows at the same time it will not
result in instant changes to sheet 2. They will only happen when you click on
it.

I cannot spend the time now to work out how to get the matched column  totals.
I think you would need to build a function to count the cells in the column
with Interior.Color = RGB(0, 255, 255).