The second developer kit is way more complete. It includes the following:

• 5'' touch screen (and connector)
• Camera (and connector)

The main advantage of this kit, however, is not the extra hardware; it is that you can use adb (the command-line tool) over the USB type C cable in the same way you would do for Android on a phone.

While that is a big advantage that makes development much easier, this developer kit has some drawbacks:

• Wi-Fi does not work unless you connect the external antenna
• The screen provided is the only way to access the system UI (there is no HDMI)

If you prefer USB deployment and debugging and don't mind the price tag, NXP should be your choice.