From https://major.io/2014/05/13/coreos-vs-project-atomic-a-review /.
[Deployment]
Coreos:
Deploy the service using a cloud image or PXE. You can use cloud-config for configuration on the cloud.
The key-value system etcd is provided, providing capabilities similar to zookeeper. It can also be used to place node information.
It provides fleet for docker container lifecycle management.
Automatic container migration and loadbalance.
Atomic:
Atomic started late. Currently, only qemu/virtualbox Virtual Machine images are available for trial use.
Provides the geard tool to deploy containers. Geard allows you to associate multiple containers into a whole. And can span multiple hosts.
[Management]
Coreos:
A/B system is provided for update.
Python/perl/compiler is not provided, but a "toolbox" fedora container is provided. You can use systemd-nspawn.
No GUI.
A management system called fleet is provided to manage docker containers.
Atomic:
Use rpm-ostree (without yum) to manage software packages. Rpm-ostree is similar to the binary version of git. It can provide multiple software versions and perform rollback.
A gui component called cockpit is provided for managing docker containers.
Atomic's basic OS is fedora and can be built on its own. Starting from fedora21, each version has a fedora atomic release.
[Security]
Coreos:
SSH key authentication.
No authentication such as LDAP or Kerberos.
No SELinux, apparmor, and audit support.
Atomic:
SELinux and svirt are available for protection.
However, cockpit cannot work with SELinux.
Ostree reference:
Http://www.slideshare.net/ I _yudai/ostree-osgit
Etcd:
Is a highly available key-value storage system, mainly used for sharing configurations and service discovery. Etcd is developed and maintained by coreos and is inspired by zookeeper and doozer,
It is written in the go language and uses the raft consistency algorithm to process log replication to ensure strong consistency. Raft is a new consistency algorithm from Stanford and is suitable for distribution.
Raft achieves consistency through election. In raft, any node may become a leader. Google container Cluster Management System
Etcd is widely used in kubernetes, cloud foundry, and fleet of coreos.
Geard:
Associate multiple containers for overall management. JSON description.
[Docker] comparison between coreos and atomic
