LED video walls are made of discrete light-emitting modules. They scale to enormous sizes, reach extreme brightness, and have a pixel pitch measured in millimetres. Stand close and you see the grid. They belong on building façades, stadium ends and anything read from twenty metres or more.
High-brightness LCD is a single panel with a backlight. It tops out around 86 inch in our line but delivers a continuous image at 3840 × 2160 — sharp at arm's length, with the kind of type and product photography that retail actually uses. Below about five metres of viewing distance, LCD is almost always the right answer.
Cost follows the same logic. For a 55 inch bus shelter panel, LCD is dramatically cheaper per unit and simpler to service. For a 30 square metre façade, LED is the only sensible option. The mistake is choosing on brightness alone: a 4000 cd/m² LCD and a 4000 cd/m² LED wall are equally readable and completely different products.