The major difference between Google's stock Android and OPPO's ColorOS is the latter's additional features. Such features include: customizable gestures for screen off, screen on, communication, a security centre, lock screen magazines, options for long screen shot, eye protection changing to a warmer color temperature, FTP Server and others. ColorOS, in some respects, looks similar to iOS made by Apple.
ColorOS removes many settings as well. The ability to restrict an app's background data usage is removed. There is no "Data Settings" entry, and users may only set alarms when mobile data reaches a certain limit, as opposed to stock Android which can also automatically turn off mobile data.