The main difference between Shells™ and other DAAS (Desktop as a Service) platforms like AWS, Citrix, etc., is that the latter platforms restrict access to your cloud desktop to only desktop/laptop environments. For example, I'd only be able to access my AWS virtual desktop from a personal laptop or desktop.
With Shells™, you can access your cloud desktop from any device with a browser and internet access. This includes gaming consoles (Playstation, Xbox), tablets, and even your smart refrigerator (eventually!) Shell™ accomplishes this by using SPICE(Simple Protocol for Independent Computing Environments), a recently (2017) released protocol that allows viewing cloud desktops from different machine architectures.
For those interested in learning more about SPICE: