Org mode started as an Emacs only thing. Over time it has evolved into a much more capable thing than markdown format. One can do almost anything in the org mode format: literate programming with code blocks which can be executed (org babel), plain text spreadsheets, scheduling and summarizing scheduled events in an agenda view, time tracking, thesis writing (it has the necessary syntax for element one needs when writing a thesis, unlike normal markdown), inter-document linking, and probably many other things.
Some time ago people started slowly bringing things to VS Code. Org mode syntax has also been separated out as "orgdown". Now finally other editors are catching up to what has been possible in Emacs for a long time using org mode. They still got a long way to go, because integration of org mode things in Emacs is very far ahead, but at least work is being done.