Docker image id in local and Docker Hub are not same

Hi, I encountered an issue recently, when I pushed an image to Docker Hub and pulled down to another machine, the image id are not same.

The machine that I pushed the docker image: Ubuntu 14.04 ppc64le, Docker 1.6.2
The machine that I pulled the docker image: Uubntu 14.04 ppc64le, Docker 1.9.1
The machine that I pulled the docker image: Red Hat 7.1 x86_64, Docker 1.9.1

They have three different Docker image id, it’s weird, does anyone know why?

@programmerq Hi, could you take a look at my question? Thanks.

Which Docker Hub image is referred to? Please post the link if available.