OS version names vs. numbers – OSX, UBUNTU

OSX
10.12 – Sierra
10.11 – El Capitan
10.10 – Yosemite
10.9 – Mavericks
10.8 – Mountain Lion
10.7 – Lion
10.6 – Snow Leopard

Source: https://en.wikipedia.org/wiki/MacOS_version_history

UBUNTU
18.04 LTS
17.10
17.04 Zesty Zapus
16.10 Yakkety Yak
16.04 Xenial Xerus LTS
15.10 Wily Werewolf
15.04 Vivid Vervet
14.10 Utopic Unicorn
14.04 LTS Trusty Tahr LTS
13.10 Saucy Salamander
13.04 Raring Ringtail
12.10 Quantal Quetzal
12.04 LTS Precise Pangolin LTS