You're still better than I am. I've heard of the latter three, I've never used a single one, and I still find it very difficult to understand what the core of the second one (Mesos) actually is because it's so shrouded in buzzwords and vague descriptions.

All I got was that it's some sort of userspace microkernel geared around abstracting the computing resources of machines (nodes) in categories like CPU/RAM/disk and expose them programmatically through a cluster-wide API. The master daemon makes resource offers to a slave daemon, which in turn runs ported applications (be it Hadoop, Jenkins, ElasticSearch or whatever) called Mesos frameworks that have to be ported to this Scheduler/Executor paradigm (sort of like a cluster resource-level MapReduce, I presume?) in order to perform Tasks.

Mesosphere is the whole stack as an integrated OS. Marathon is pretty easy to understand - it's an init system/framework supervisor that operates on a higher level of abstraction than simple OS processes.

But yeah, it's a pretty tangled mess.