I may be mistaken but AFAIK plugins are not always at feature parity with the full jetbrains IDEs. For example the rust plugin in intellij did not support debugging but the one in CLion did (I think this is fixed now).
The python plugin in intellij was a little inferior to Pycharm for Django (pycharm had deeper support for the django ORM) and so on.
I think the reason for the difference between clion and idea for the rust plugin is that clion seems somehow different "on a lower level". It still has support for profiling and valgrind, which Idea lacks [0].
Regarding Django, do you have some examples? I'm admittedly not a hardcore Django user, but I haven't seen any difference between the two.
CLion isn't the best comparison here, as there are some architectural differences between CLion and the other IDES (IntelliJ, PyCharm, WebStorm, etc), which is the reason there isn't a C/C++ plugin for IntelliJ.
The python plugin in intellij was a little inferior to Pycharm for Django (pycharm had deeper support for the django ORM) and so on.