Ecosystem, but not much more. Code is faster and has very good intellisense for JS. Though it's still in Beta it's been very stable and a pleasure to use.
Indeed, the VSCode intellisense for JS is amazing, especially after the latest February release.
Given it is open source, couldn't Atom just re-use VSCode's intellisense?
I use and like both. VS Code is definitely faster, but I love the tabs in Atom. As someone who grew up more in a browser than in a terminal, it just feels very natural. There are also more packages available within the Atom ecosystem, or at least, discovering useful packages and searching through them is better.