Difference between potentials in potential.txt file and Average_surface_potential_of_node_1_(V_,_s)__ElecNode1_Potential.txt file

Hello everyone,
I am trying to understand the difference between two potential outputs obtained from my simulation (both files from .Simulations/Run1/NumKernel/Output directory)
In the file “potentials.txt”, I have values such as:
• elecNode1ground
• elecNode1surface
while in the file “Average_surface_potential_of_node_1_(V_,_s)__ElecNode1_Potential.txt”
I have:
• esn 1 average
• esn 1 ground
• esn 1 min
• esn 1 max
What is the difference between:
• elecNode1ground (from potentials.txt) and esn 1 ground (from the Average Surface Potential output)?
• elecNode1surface (from potentials.txt) and esn 1 average (average surface potential)?
I noticed that these quantities are not always equal, especially during the transient phase, but also after reaching convergence. What exactly does each quantity represent in SPIS, and why do their values differ?
Any clarification would be greatly appreciated.
Thanks!

Alessandra