Cloning the iso file to a USB pendrive
dd like you describe is cloning, which is a simple an reliable method that works with all current Ubuntu family iso files in order to create USB boot drives, and 64-bit systems work in both BIOS and UEFI mode.
You need elevated permissions, which you do by running with
sudo. I think the following command would do what you want
sudo dd if=~/Desktop/xubuntu16.04 of=/dev/sdx bs=4096
where x is the device letter of the target drive. It is extremely important the get the correct letter for the target drive, otherwise you might overwrite a drive, where you store the family pictures and some other very important files.
dd is a very powerful but also very dangerous tool, because it does what you tell it to do without questions, and a minor typing error is enough to destroy your family pictures.
There should be no partition number, so
/dev/sdx1) because you want to clone from the iso file to the whole drive and point to the drive's head end, (not to a partition). In my experience it is fast in many computers to write with the block size 4096 bytes.
Safer cloning tools
I would recommend that you use a tool that helps you identify and select the target drive and with a final checkpoint where you can make sure, that you will write to the correct drive.
'mkusb' is such a tool that works in all current Ubuntu versions. It wraps a safety belt around
dd. See this link
The Ubuntu 'Startup Disk Creator' in Ubuntu 16.04 LTS and newer versions is also a reliable cloning tool to create USB boot drives with Ubuntu. (Earlier versions of the Ubuntu 'Startup Disk Creator' are buggy.)
- Another alternative is 'Disks' alias