Imho, the main advantage of Parallel is that it can execute the tasks on multiple hosts, straight from the man page:

> GNU parallel is a shell tool for executing jobs in parallel using one or more computers. The typical input is a list of files, a list of hosts, a list of users, a list of URLs, or a list of tables.

This gives an (artificial) example of the power of GNU Parallel over xargs: https://unix.stackexchange.com/questions/405552/using-xargs-...