Which is better for gaming?

The LG 91A. It runs 120 Hz natively at 4K and has four HDMI ports. The Xiaomi reaches 120 Hz only through Game Boost at 1080p or 1440p, so 4K gaming stays at 60 Hz.

Which has the better picture?

The Xiaomi publishes 384 dimming zones and up to 1,200 nits, which points to strong contrast and highlights. The LG does not publish zone counts, but owners consistently praise its brightness and color. The LG's larger 75-inch panel is the bigger draw for a main room.

Is the LG worth stepping up to over the Xiaomi?

Yes if you game, watch sports or sit far from the TV. The extra size, native 120 Hz and four HDMI ports are real advantages. The Xiaomi is the more sensible pick for a smaller room or a Google TV household.

Which smart platform is better?

Google TV on the Xiaomi has broader app coverage and built-in Assistant and AirPlay. LG's webOS is fast and adds 400+ free LG Channels, but its app library is narrower.

Neither maker publishes a lifespan figure. Both are LED-backlit sets with similar panel technology, so expected life is comparable. The LG's higher rating count gives more owner feedback to judge by.

Do both support HDR and voice assistants?

Yes. Both handle HDR, and both work with Google Assistant; the LG also supports Amazon Alexa. The Xiaomi adds Dolby Vision-style formats through HDR10+ and HLG.

LG Class 91A QNED evo Mini LED 4K TV vs Xiaomi TV S Mini LED 65-inch

Buy the LG 91A if you want the brighter, smoother 75-inch set for a living room with sports and console gaming. Its Mini LED panel, 120 Hz native refresh and 4 HDMI ports beat the Xiaomi on motion and connectivity, and its 111 owner ratings average 4.6 with praise for brightness and setup. The Xiaomi S Mini LED is the smaller 65-inch set with 384 dimming zones, up to 1,200 nits and Google TV; it suits a bedroom or a Google household, but its 60 Hz panel and 120 Hz Game Boost only at 1080p/1440p make it the weaker gaming pick.

Choose the LG 91A if you want a 75-inch Mini LED with native 120 Hz, four HDMI ports and webOS with LG Channels.
Choose the Xiaomi S Mini LED if you want a 65-inch QD-Mini LED with Google TV and AirPlay in a smaller room.

Prices

LG Class 91A QNED evo Mini LED 4K TV: $499.99 at DoorDash (last seen Nov 12)