Besides the 12GB of RAM (over the original’s 4GB) and 256GB of storage (the original had only 32GB), this leak outlined that the Switch 2 will come with an 8-inch display, HDMI 2.1 support ...
That same source also indicates that the Nintendo Switch 2 could offer hugely improved battery life, in addition to a 120 Hz refresh rate with a 7-inch OLED display. In terms of overall design ...