Direct LED is a lot like "full array" but there's a big difference tgm.
In what we all think of as full array, a fairly substantial number of LEDs are very, very close to the screen providing illumination. There is diffusion of light going on (obviously) to maintain uniformity, but the amount of LEDs is high.
In direct LED, there is intentionally a gap between the LEDs and the screen -- much greater than in full array. A substantially smaller number of higher-output LEDs are used and very actively diffused to illuminate the screen. A direct LED is a lot like an old CCFL set where the CCFLs are replaced by LED light sources. It's also cheap to make.
A full array set -- because of the reliance on many more LEDs -- is more expensive than a "direct LED" set. It can be made much thinner (although not as thin as edge lit typically) than a direct LED set, but at a price.
Incidentally, you could locally dim a direct LED set too. It'd be better than the bogus edge-lit "local dimming" sets. But given that direct LED is about low cost, I doubt we'll see much (any?) of that ever happening.
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.