The highest display resolution of the Samsung UN55HU8550 is 4K Ultra HD. That's over four times the display resolution of the most common HD type of Full HD. 4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
A 4K Ultra HD HD type is actually the best display resolution amongst all TVs that are a comparable age to the UN55HU8550.
A Full HD HD type is the worst display resolution across comparable types of television.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.