A Hacker News forum thread discusses the similarities and differences between Vagrant and Docker: " It is unfortunate that so many people compare Vagrant and Docker. While there is overlap, Docker is mostly not viable as a dev environment tool alone, so it isn't a fair comparison. The main reason is because you have to be using Linux (and a recent Linux) as your main dev system, and in practice this is very rare. Move beyond indie developers and for all intents and purposes Linux desktops are non-existent (Vagrant is in use by companies like BBC, Expedia, Intuit, etc. and I can tell you most devs don't know how to use Linux let alone run it as their primary dev platform).
"BUT, I agree that putting your dev environment in a Docker container is absolutely _amazing_, and there is a KILLER Vagrant/Docker combo."
See the full discussion at Hacker News.