I will like to know the difference between these letters on vehicle.
XL, LE GLS, LS etc

Those are trim level designations for vehicles with varying levels of standard and optional equipment, and they vary from one manufacturer to the other. A standard feature on one trim level might be an option on the other, for instance,toyota Camry XLEs have standard leather interior,power moonroofs,power adjustable seats,standard alloy wheels and more standard features than the base 'LE' trims, The sporty SEs have aggressive looking body kits with rear spoilers and stiffer suspension settings. A good number of LEs have fabric interiors and lack alloy wheels (U̶̲̥̅̊ hv to pay extra for that). In some vehicles, U̶̲̥̅̊ can only get specific powertrains (engine/gearbox combo) in certain trims. Beware of car dealers who try to exploit potential clients by calling base models 'full option(ed)'.

Thanks