To add a bit more, iXsystems makes enterprise NAS systems, and develops TrueNAS (formerly FreeNAS and TrueOS) which has ZFS as one of it's main features.
Klara systems is more of a development and support consultancy firm for FreeBSD and ZFS.
Just two different independent companies. Like Netflix and Apple TV for example.
Competitors, but they both participate in OpenZFS development. Yet another success story for open standards.