The difference is that some technologies use encapsulation and abstraction to manage complexity, while others vomit megabytes of configuration on the floor.

Of course Docker in an enterprise will never be as simple as running a Rails app on your Macbook, but it provides an encapsulation primitive that looks as powerful for deployment as object orientation and functional programming were for development.

SICP lecture #1: we manage complexity through means of abstraction and means of combination. Docker is a means of abstraction, and it leaks less than the others we have so far (Chef cookbooks, etc.) We haven't quite figured out what the means of combination is. It won't be trivial - writing programs certainly isn't - but it will be better than handrolled assembly.