Yeah, for a while we had to say ES2015/ES6 in all of our blog posts etc. but hopefully soon things can settle down. Especially when it gets to ES2016/ES7 and above, having the year in the name will be super convenient (like Ubuntu version numbers)
Yes , ES2015 is ES6. AFAIK ES2015 is now the official name of the spec.
They are using some, but not all, features
supported by Babel to compile ES6/ES2015 syntax to ES5.