Using the analogy of a lake, deep movement involves moving down through the water, whereas skim movement involves skimming across its surface.
Deep movement is much less visible as it occurs below the surface.
Skim movement operates on the surface. It gives the impression of 'great' movement as it skims rapidly across, unencumbered with much necessity to interact. Skim movement is bold, sweeping, exciting, colourful, full of surface energy and heat. All flash and no substance'. Deep movement can be seen as stodgy, boring, unadventurous, stuck in the mud.