While they share the same name and many of the same features, Cyanogen OS and CyanogenMod are actually two distinct Android ROMs. The main distinguishing factor is that whereas the latter is mostly developed by an open community of users, the former is a commercial product based on the CyanogenMod project but managed and updated by a private company. On top of that, Cyanogen OS also includes a handful of exclusive apps that are preinstalled on retail smartphones like the Yu Yureka or the OnePlus One and aim to improve user experience on those devices.
However, Cyanogen has just announced that it will be shrinking the gap between Cyanogen OS and CyanogenMod by bundling a suite of apps into the Cyanogen Apps Package (C-Apps for short) to be installed on any CyanogenMod device. For now, these include Audio FX, Theme Chooser, Theme Store, Gallery, Email by Boxer, and Dialer with Truecaller, but Cyanogen promises more apps will be added in future updates. The C-Apps package also allows users to create a Cyanogen Account, which enables access to the Theme Store and TrueCaller functionality, as well as providing the ability to remotely locate, lock, and wipe a device.
C-Apps is offered as an optional download that can be flashed on any device running a build of CM 12.1 dated November 10, 2015, or later. It's possible that these apps will also work on other variants of Android, but since they weren't designed to run on anything other than CM, you shouldn't be surprised if they don't work as expected.