The main difference that users notice between AIM and ICQ is that ICQ issues a Universal Internet Number, or UIN, whereas AIM lets users choose their own screen name. Both AIM and ICQ are owned by the same corporation, Time Warner, so AIM users and ICQ users can freely message each other without the need of having to download any other software. | The main difference that users notice between AIM and ICQ is that ICQ issues a Universal Internet Number, or UIN, whereas AIM lets users choose their own screen name. Both AIM and ICQ are owned by the same corporation, Time Warner, so AIM users and ICQ users can freely message each other without the need of having to download any other software. |