At a high level, that's about it, and it is huge. Sketch is macOS only. Hell, this page comes up when you google "sketch for <not macos>": https://www.figma.com/sketch-alternative/
I recently came across a Windows-only app called Lunacy which offers Sketch file import and editing for Windows users (I haven't tried the app).
The published Sketch file specification [1] is what allows Figma and Adobe XD (and Lunacy) to import Sketch files. Ironically, neither Figma or Adobe XD publish their file formats.
I think where Figma is pulling ahead of Sketch (in terms of usage behaviour) is that it is being used by more than just designers. In fact, Figma is beginning to encroach (possibly unintentionally) on digital whiteboard tools like Miro and Mural.
I recently came across a Windows-only app called Lunacy which offers Sketch file import and editing for Windows users (I haven't tried the app).
The published Sketch file specification [1] is what allows Figma and Adobe XD (and Lunacy) to import Sketch files. Ironically, neither Figma or Adobe XD publish their file formats.
I think where Figma is pulling ahead of Sketch (in terms of usage behaviour) is that it is being used by more than just designers. In fact, Figma is beginning to encroach (possibly unintentionally) on digital whiteboard tools like Miro and Mural.
[1] https://developer.sketch.com/file-format/