Long-filler refers to whole tobacco leaves which run the length of the cigar. The Premium and perchance even Super Premium offering (if donning a cape and mask, natch). Tobacco is nature, nature doth vary some, but generally think this in terms of size: usage of long-fillers birthed common cigar lengths.
SHORT-FILLER:
Short-filler: chopped tobacco. In lieu of long-filler's whole leaves, short-filled cigars use trimmings, choppings and 'other' plant/leaf parts. Think less than Premium and hotter more un-even burns, particularly. Think Further on Each of the Eleven (11) Commandments of Cigar Etiquette V. Machine-mades oft go here, with a double-binder tact.
MIXED-FILLER:
Mixed-filler involves, guess what -- a mix of long and short fillers. Oy, the brilliance. One mixed-filler method, the Cuban Sandwich approach to manufacture, sees short-filler rolled into long-filler leaves. Ah, the art of the $2 stogie. I cannot say soitenly that Topper's Ebony, this brief article's impetus, does exactly that.
POST-SCRIPT: Read, please, my "Topper Original Handmade Ebony - Cigar Review."