Atom has a richer API (though poorly documented at present) with the design goal of allowing greater control of its UI. Atom's 'closed' part is unknown at the moment, but I get the sense it's smaller. in the gutter) or manipulate the statusbar beyond basic text. For example, Sublime plugins can't interact with the sidebar, control or draw on the editing area (except in some limited ways eg.

Apart from skins/themes and colourisers, the API currently makes it difficult to modify other aspects of the UI. The 'closed' part of Sublime includes the API and UI. Though I expect improvements in Atom as it matures, design & platform choices limit performance. Though similar in UI and UX, Sublime performs significantly better than Atom especially in 'heavy lifting' like working with large files, complex SnR or plugins that do heavy processing on files/buffers. Atom is written in Node.js/Coffeescript and runs under webkit, with Coffeescript being the extension language. Its core is written in C/C++ and a number of its features are implemented in Python, which is also the language used for extending it. Sublime is binary compiled for the platform. In addition to the points from prior answers, it's worth clarifying the differences between these two products from the perspective of choices made in their development.

What is a text editor examples