What is EFI drive in sense of system backup

In my former laptop (HHD, MBR) I regularly backed up the system, i.e. drive C:\. In case Windows crashed or seriously malfunctioned I only restored the previous version. I didn’t bother with the data drive on the same disk; that was never affected whatever happened to the OS.

Recently I bought a new laptop (SSD, GPT). I migrated my system, yet I found an additional drive A:\ on the disk. I found out it is an EFI drive for boot, independent of the OS. If so, I still should back up C:\ only, leave the EFI partition just like the data partition; restore would only give back the very same.

When I started the backup though, Paragon HDD Manager offered to take A:\ along with C:\. Why? Are these two drives still coupled somehow? What is the advantage / disadvantage of backing up both or C:\ only?

Thanks a lot.