Like Sublime Text, it's somewhere between an IDE and a text editor. For example, both Sublime Text and Atom have a TypeScript plugin that uses the TypeScript language service to highlight compilation errors as you type, and to provide semantically-correct autocomplete suggestions. These are features typically expected in an IDE.

However, neither integrates with a debugger like a traditional IDE. You'll likely drop to a terminal or external tools to run / test / debug your program. (I'm sure they both have a plugin to make terminal commands a keyboard shortcut away, though.)

Hope that helps. It's a fantastic editor, although it can be a bit RAM heavy on my aging MacBook Air.