Flash memory and memory refer to the space of the temporary storage registers such as XNV, NV, V, etc.
Internal user storage refers to the space where the formula will be output to an internal location, which can be seen through file transfer and is considered internal user storage.
Project memory refers to the capacity of the project plus the firmware.
You need to check the backup memory option to perform power-off retention (automatic data retention for a 1-minute interruption).