[tinco]

It could be that their communities have different philosophies about containers, but this is not a technical difference. I think Docker added support for live migration recently too (the Doom demo on that recent Docker con right?)

They are built around the same set of kernel features and as far as I can see offer exactly the same abstractions.

For example Phusion Baseimage is a Docker baseimage that's similar to an OpenVZ container in the sense that it emulates a full running Ubuntu environment. It has is uses but the Docker community rather sees containers that encapsulate a single application with no external processes.