Android Studio is a special build of IDEA focusing on Android. It’s like PyCharm. You get IDEA with some features removed and certain plugins pre-installed and defaults set. Personally I like using their specific IDE’s for their tasks, but I could imagine that you can easily replace Android Studio with IDEA and not have any difference (besides more features being available).
When you want to do Android and non-Android development, do you need both IDEs, or can one fully replace the other?