Qt Creator is an open source, cross-platform integrated development environment (IDE) designed to create applications with the Qt application framework. It is designed to be very easy to use, with intuitive user interfaces and powerful development tools. Qt Creator has powerful code editing features, such as syntax highlighting, code completion, and refactoring. It also includes a visual debugger, a profiler, and a designer for creating user interfaces. Qt Creator supports multiple programming languages, including C++, JavaScript, and QML. It also includes integration with version control systems, such as Git and Subversion, and support for development on mobile platforms. Qt Creator is available for Windows, Mac OS X, and Linux.
QtCreator is a full IDE, while Atom is just a text editor.
Atom is a text editor, while QtCreator is an IDE.
Project management, add-ons, code refactoring.
Discontinued Aptana is still under development on GitHub but the latest version, 3.6.1, was released in October 2014. It lacks Java 8/9 features, as well as more recent JavaScript and HTML 5 features.
Discontinued Appears to be abandoned. The last release was January 2016
Atom is a text editor, while Qt Designer is a UI creation (design) software.