CoreELEC backups save the contents of three system directories:
/storage/.cache
/storage/.config
/storage/.kodi
If any of these directories have hardware-dependent configurations, recovering the backup to another device may have problems. The only way to find out is to try it yourself.
I use a N2 and a C4 and have restored the N2-backup several times to the C4.
No problem. All libraries, addons, settings etc were restored on C4 correctly.