The ScanSnap iX1600 is an upgraded version of the iX1500 model. Key improvements include faster 40 ppm scanning speed, higher color depth up to 96-bit, and support for longer 220" scan lengths. It also adds convenience features like animated OLED operation guides. Both models have core features like OCR, document management, and cloud connectivity. The iX1600 brings faster performance and slightly expanded scanning capabilities at a higher price point.