You could have done this yourself , but what the hell:
https://wiki.mobileread.com/wiki/Kobo_Firmware_Releases
https://blog.the-ebook-reader.com/20...-models-apart/
And from:
https://wiki.mobileread.com/wiki/Aura
The Aura Edition 2 was updated in late 2017 with a hardware refresh. The CPU has been updated to the i.MX 6SLL. Externally, the two versions are identical. The serial number number can be used to tell them apart. If the 7th digit of the serial number is a "2" it is the second version, otherwise it is the first version.
EDIT: Why is this not posted in the regular Kobo forum ?