Greenfoot vs Eclipse Che

Greenfoot is free to use.

Greenfoot was developed as a way to teach Java to first time programmers.
Greenfoot provides for variety of additional resources such as tutorials and community support.

Built-in terminal with root access so you can make changes to your running machines. Being able to SSH into the workspace so you can use a desktop IDE is handy.

You can package up custom commands with your workspace and then use them (or share them) with everyone else.

You can choose from pre-configured environments for Java, Javascript, C++, PHP, C#, etc., or you can define your own by dropping in a Dockerfile - makes it easy for simple and complex projects.

Projects can be easily imported from any Git or Svn repository hosting service.

The workspace in Che includes project sources, IDE and the runtime. So if you hand your Che workspace definition to another user and they execute it they will get everything they need to build, run and debug the project.

Also the runtime is in a Docker container so it will work even if the second user is on a different OS than the original user who shared their workspace with them.

Che does a nice job to automatically map the service:port running in the Docker container (e.g. tomcat on 8080) to the Docker port it actually uses (something in the ephemeral range). You never need to figure that out - it's just made available when you run your server.