Different display technology is the biggest. Remarkable 2 uses e-ink (like Kindle) where Daylight uses reflective LCD tech. Advantage to RLCD is it is super fast (you can actually watch videos, scroll and zoom are better). While eink has improved, there is still some lag. Also, remarkable 2 doesn't have any kind of light, where Daylight has very tiny perforations allowing them to light the screen from behind in an amber color (no blue light). This is different from Kindles that use tiny lights in the edge that shine onto the eink.
On software side Daylight is looking to be more open (founder said they will offer root kits) where Remarkable seems very closed (even has a subscription service for cloud storage and syncing). Daylight is version of Android so you can load in all kinds of apps if you want.
