Amines and esters are different forms of the active ingredient 2,4-D.  They primarily change the handling characteristics of the product and absorption of the molecule in the plant, the different forms kill plants in the same way.   The difference between LV4 and LV6 is the amount of herbicide in the formulation, LV4 contains 4 lbs 2,4-D per gallon whereas LV6 contains 6 lbs per gallon.  Use rates of an LV6 would be lower.  One big difference between amines and esters is that esters can be volatile, evaporate following application and move from the target site.  The LV (low volatile) formulations minimize this, but under certain conditions can still move due to volatilization.  Suggest reading the label and choose a product that is registered for the intended use