Hi,
balenaEtcher is a tool for flashing disk images. And a disk image contains partitions, type of those partitions (fat, fat32, ext3, …), data, etc. You can look at it in this way - simplified explanation - balenaEtcher just copies bit by bit from the image to your SD card. There’s no formatting, partitioning, etc.
If you look at our device images they do contain following partitions:
- resin-boot fat32
- resin-rootA extFS
- resin-rootB extFS
- resin-state extFS
- resin-data extFS
resin-data partition is a small one and it’s going to extended during the first boot to cover rest of the SD card capacity.
If you flash balena device images, you’ll end up with fat32 partition followed by couple of extFS partitions. If you flash any other image, like mentioned libreelec, you can end up with different partitions and different partition types (fat, ntfs, fat32, extfs, …).
In other words - partitions, types, data, … all this information is provided by the image.