So the B8 is last years low end OLED model. Image quality is very similar to the B9 - The main differences are HDMI 2.1, eARC, variable refresh and Apple support. Other minor differences are an incremental processor improvement, thinner bezel, improved sound, a more stable stand.
HDMI 2.1 is important if you’re going to buy a next gen console - PS5 or Xbox 2, as the new features add support for faster and variable frame rates.
[It all comes down to bandwidth: The current bandwidth capacity for HDMI 2.0 is 18 Gbps, but HDMI 2.1 clocks in at a robust 48 Gbps. This increase in bandwidth allows HDMI 2.1 to transfer way more information; in a nutshell, this means higher-resolution video and higher frame rates]
Thanks.