Difference between an AppImage and an archive file

Many applications (IntelliJ IDEA, PyCharm, Android Studio, etc) are available as a tar.gz or tar.xz files. They do not need to be installed. You just need to extract the archive file and run the application. On the other hand there are AppImages. By running an AppImage, the AppImage is temporally mounted on \tmp directory and then is executed. You can also extract the AppImage like any archive file and run the application. So my question is what is the difference between an AppImage and an archive file?