A:Answer The difference between NANO Series 75 and Series 90 are that the 90 Series is a more advanced model. It has an IPS panel, greater output power, a 2.2 speaker system, 2 HDMI inputs that support 4K@120Hz, full array dimming, and a faster processor. Please see the link for a side by side comparison, https://www.lg.com/us/compare?bizType=B2C. ^Daphane