Main difference is that we are more opinionated (in terms of configurations) and sort of do the scrolling and sorting out for you – hopefully a bit smoother as a user experience. We sort out bad machines immediately. We're also directly working on making compute from unknown high-end data centers available, there's a lot of unused compute out there! See gpulist.ai

Also, don't know if vast.ai does this, but with us you can have 6 user sessions on your machine if you have six GPUs, so granular utilization is possible.