IDE is based on Theia (https://theia-ide.org), i.e. VS Code with cloud-first mindset.
The other options are just IDEs in a browser where you still have to hammer together your own setup + build manually every time.
We couldn't address it in time for the launch, so basically all the website's pricing options currently point directly to where you can buy them in the app, which implies a GitHub sign-in (where only a valid email is requested, NB).
We're planning to add un-authed pages with more info about each plan, but we also prefer spending our time on improving the developer experience rather than on payment options, so it may take a bit of time.