Supercomputers cost a lot of money and are generally funded for specific reasons. Supercomputers are generally not very general purpose, but rather particularly built to be as good as possible at one class of task. Some computers will have a lot of CPUs, some will have a lot of GPUs, some will have a lot of both, and some will have completely different types of units that are custom built for a specific task.

It all depends on the supercomputer, but some aren't designed to excel at the ML algorithms. Any of them will do wayyyy better than your home computer due to their processing power, but many will be relatively inefficient.