You need a loop to collect the scores, a variable to store the highest value found, and an array to store them in. Then another loop to find the difference between each value and the highest value that you stored in the variable in the first loop.
You have to write the code. We don't do your homework for you.
For Each ctrl As Control In Me.Controls("pnlMainPanel").Controls
If ctrl.GetType Is GetType(System.Windows.Forms.Panel) Then
For Each subCtrl As Control In ctrl.Controls
If subCtrl.GetType Is GetType(System.Windows.Forms.TextBox) Then
If subCtrl.GetType Is ...