The chopped sandwich is defined by a technique applied to a finished sandwich rather than by anything in it. Every component, the meats, the cheese, the lettuce, the tomato, the pickles, the dressing, is built as if for an ordinary sandwich and then taken apart: piled on a cutting board and worked over with a knife until the whole thing is reduced to a uniform, fine, dressed mince before being scooped back into the bread or a wrap. Nothing is added that a normal sandwich would not have. The chop is the only variable, and the chop is the entire point.
The reason the technique works is distribution. A layered sandwich delivers its ingredients in strata, so one bite is mostly meat and the next is mostly bread, and the dressing pools wherever it was spread. Chopping erases that. Every component is cut to roughly the same small size and tossed together so the dressing coats all of it evenly, which means every bite carries the full ratio of the sandwich at once. The cost is structural: a chopped filling has no internal architecture and will spill, so the bread has to change to compensate. A sturdy roll split as a deep boat, or a wrap rolled tight and sealed, becomes a container rather than two faces, because the filling can no longer hold itself in a stack. The chop also rebalances texture deliberately. Crisp lettuce and pickle are cut small enough to thread through the soft meat and cheese instead of sitting in a separate layer, so the crunch is dispersed rather than encountered. Done well the filling is loose but not wet, the knife having married the dressing into the solids rather than drowning them; done badly it slumps into a paste, which is the failure mode the technique constantly flirts with.
The variants are recipe-level rather than structural, because the method is portable to almost any filling. An Italian sub chopped, a chicken-and-bacon ranch build chopped, a tuna salad pushed further than it already is. The bread is the only thing the technique forces a real decision on: a deep roll or a tight wrap, never a flat slice. It belongs to the broad family of regional and improvised American sandwiches, and those relatives deserve their own articles rather than being crowded in here.