The lowest cost version is reduced to the max as it only features a power input and Ethernet output. Other versions add interfaces like the GPIO connector, CSI-2, SD card and more. The NX versions integrate an enhanced power supply with 5V and up to 8A.
An SSD can be ordered additionally: https://auvidea.eu/product/71101/
Please note that JNX84-LC has no M2. SSD interface.