You can get ZFS on Linux, just not along with Linux due to licence issues:
http://zfsonlinux.org/
http://zfsonlinux.org/faq.html#WhatAboutTheLicensingIssue
ZFS is licensed under the Common Development and Distribution License (CDDL), and the Linux kernel is licensed under the GNU General Public License Version 2 (GPLv2). While both are free open source licenses they are restrictive licenses. The combination of them causes problems because it prevents using pieces of code exclusively available under one license with pieces of code exclusively available under the other in the same binary. In the case of the kernel, this prevents us from distributing ZFS as part of the kernel binary. However, there is nothing in either license that prevents distributing it in the form of a binary module or in the form of source code.
Comparing them is beyond me and I've decided to reset the OpenSuse defaults and stick to Ext4 rather than the recommended BTRFS / XFS and sit it out until 13.3.
Lots of good reading if you do a Google versus search.
https://rudd-o.com/linux-and-free-software/ways-in-which-zfs-is-better-than-btrfs