That’s absolutely wrong. The only thing that you’ll notice in IDEA is that it makes certain assumptions about Java (e.g vocabulary and certain menu items are Java-related), but otherwise the functionality is the same.
The language specific apps also seem to get updated before the language plugins do.
I used to use IntelliJ Ultimate, and had to wait a while before getting new features announced for PhpStorm, for example.
I now just use PhpStorm for PHP and GoLand for Go, instead of attempting to use IntelliJ for all languages. I spend less time configuring IntelliJ for each language and get updates on release day.
JetBrains has an "everything" licence that I was able to migrate to from IntelliJ Ultimate.
Python support inside IDEA is not the same as Pycharm, please don't confuse people. If you want to do Python development, use PyCharm. For Java, use IDEA.
I have used IDEA for 4 years doing Python development. Now I am using PyCharm, where the only difference is that it doesn’t support multi-module projects.
Please specify the differences as I am seeing none.