Samsung QLED televisions in 2018 go from Q6 (intro) to Q9 (highest model). Main differences: Q8 &Q9 have the full array of backlighting and 60 watt audio speakers whereas Q6 & Q7 only have edge lit LED back lit display and 40 watt speakers. Q6 is only model around 1000 nits of brightness whereas Q7-Q9 have 1500-2000 nits of brightness (extremely bright). Lastly, the local dimming areas grow in number from Q6 to Q9...since Q9 has hundreds of dimming areas enhancing blacks, bright objects don’t have a halo effect across dark landscapes. All models are 4K image quality but those are the main tech diffs other than price point!