So you are saying the JU6 series have a poorer refresh rate panel? Is that not down to the software though? Surely a 4K panel is technically superior but the software and lighting of that panel is what can separate that from being a great or mediocre panel.
I know you say the JU6 series has a poorer refresh rate but according to Leo Bodnar tests its also one of the highest performing Samsung TV's for gaming with around half the input Lag of the H6400 and a third of the HU7500 - according to reviews - although I have no way to test these myself.
I personally have both a 55HU7500 and a 48H6400 so can't really comment on the JU6400 and its 'qualities'. I know its classified as an entry level TV for 4K. 3D (as both my sets have) may require better software to utilise but wouldn't the actual panel be the same - either 4K for 4k sets (like the JU6400, HU7500 etc) or the 1080p screens in H6400 and similar non-3D sets.
As Samsungs seem to have the same picture management system - obviously with a few differences depending on whether they are 3D or not and price point (more expensive models have local dimming) but the core picture management is the same - which leads me to believe the main difference is in the software and related electronic components behind the screen.
There are a LOT of similarities between various levels of Samsung TV's - regardless of 3D or 4K. I can easily see Samsung using the same 4K panel in all their 4K TV's but the difference is in the electronics, lighting system (direct or edge) and software driving those panels. All seem to have the same core software and depending on the additional features, that related 'software' added on top.
1. The refresh rate of the panel is not a software thing, although some computer displays can be 'overclocked' to a higher refresh rate.
Here you can read more about the panels used in the
Samsung J (2015) lineup.
2. Input lag is just a delay between when a frame is generated and when it starts showing on the display. It is only relevant for interactive content, mostly fast paced games. I'm not really concerned about this.
3. The response time is the speed at which a pixel transitions from the color of the old frame to the color of the new frame. It is a trait of the panel and the drive circuitry (not image processing).
4. Motion handling and motion blur are determined by the whole package, not only the panel. Please read
here before continuing with my post.
mdrejhon seems to know what he's talking about, but a few things are not really clear to me.
Considering a sample and hold display like the LCD is (you display an image and keep it there for one frame time), the most intuitive way to make it more 'real-life' is to increase the refresh rate and, very important, display video filmed at that rate (see the example with the panning scene over at hardforum). Apparently you would need close to 1000hz before the point of diminishing returns. The frame time would be 1ms and your brain wouldn't need to do any kind of interpolation. Unfortunately we can't make panels that fast and must find some workarounds.
The problem with 60hz LCDs is that it ends up displaying a static image for 1s/60 = 16.67ms and then it goes to the next image. This very high frame time is perceived as motion blur by our visual system as it cannot interpolate well between the frames. The magic, from what I gather, is that you can trick it into interpolating very well if the static images are shown for a smaller amount of time, much smaller than the frame time. So, you show the image for 1ms and go dark for the rest of the frame (15ms). This is similar to the way a CRT works, except that a CRT scans the screen so the interval for each pixel is lit has an offset. It would also behave as a CRT and have apparent flicker at 60hz so you have to go 120hz. At 120hz one simple way to improve on things if you have a 60fps video is to do black frame insertion and black out every each other frame. To go beyond this you have to use a scanning backlight (like
this) which is more like a CRT.
Hopefully I didn't mess this up entirely and if I did, I guess someone will correct me.