It's a completely different idea. In the article they mention 2 other similar paid apps.

Celestia is quite focused on accuracy and while it has many educational overlays and add-ons, it's a practical tool for astronomy geeks "in the know". It's used by the ESA to interface with their Space Trajectory Analysis tool.

Celestia is free and OSS (GPL). Celestia receives no funding and all support AFAIK has been made in terms of sharing knowledge and source code. Celestia is, in short, an old school pure Open Source project. This has pros and cons, but I'd say it's pretty f*ing amazing.

It's amazing, but I'd much rather fund Celestia than a closed-source semi-competitor that runs only on Windows.