Equalizing
Charging at a higher than normal voltage to stir up the electrolyte in the cells and attempting to bring all to the same 'specific gravity' reading
De-desulfating. Attempting to remove lead sulfate from the lead plates and return the sulphur to the electrolyte solution
This does two things , cleans the plate surface and restores electrolyte strength
The electrolyte is diluted sulfuric acid
The difference is merely technical
You can have equal readings in all cells with out having full strength electrolyte
And still have sulphation on the plates
The process of de-sulfation is to remove all the lead sulfate
This is know to sometimes cause plate erosion, not just increase electrolyte strength