I was searching about the information regarding difference between online help and user guide .
I have summarized the huge information I got related to it. I think it provides the crux of the matter.
Online Help:Online help is nonlinear and precise. It is context sensitive and provides hyperlinks, unlike user guide. It can be updated. It is a form of user assistance. It is created by using help authoring tools. There are many tools like, Robohelp, HTML Help, etc.
User guide:
User guide has to be linear and elaborate. It includes screen shots or images.