Main differences between mesosphere and coreos

Question

Firstly, is it correct to compare these two products? If yes, what is the main difference between them?

Answer 1

CoreOS is a Linux based operating system which includes some distributed systems tools like etcd, locksmith, flannel, and the orchestration tool fleet,.

Mesos is an orchestration system which runs atop a Linux operating system and handles the scheduling, fault tolerance, and scaling of an application or series of applications.

Mesos can run atop CoreOS in a series of containers (https://github.com/veverjak/coreos-mesos-marathon), and CoreOS can be used without Mesos.