It's really unfortunate how tutorials still spell out all the basics to keep the beginners with them, but then rely on the old-fashioned device names when it comes to writing images. Using sda is fine if you're experienced and know what drive has what name, but technical references should stop relying on them already. It's not like you're getting some useful cross-platform compatibility out of old-fashioned commands or anything, every modern Unix has its own way to specify disk names.