What's the difference between "docker run -v ..." volume and Dockerfile VOLUME?

I have successfully been able to share folders between a docker container with volumes using docker run -v /host/path:/container/path ... But my question is what the difference between this and using the VOLUME command in the Dockerfile VOLUME /path I am using an image that has a VOLUME command, and I'd like to know how to share it with my host. I have done it using the -v command above, but I did