Shift registers and feedback nodes are used when you want to pass values from the currently executing iteration of a loop to the next one. This snippet demonstrates how they are both used and that they are functionally equivalent. The feedback node is a good candidate to be used in the Teleop sub VI where no loop structure is available to implement a shift register.
Interested in going through more training on LabVIEW Basics check out our Basic and Advanced Training slides here.
Here is a white paper on how to use a snippet in your program.