Hello Hassan

There is no difference between Office Forms server in MOSS 2007 and stand
alone Office Forms server. Only MOSS 2007 provides some extra features

Office SharePoint Server 2007

Office SharePoint Server 2007 relies on the Microsoft Windows SharePoint
Services 3.0 technology to provide a consistent, familiar framework for lists
and libraries, site administration, and site customization. Any features that
are available in Windows SharePoint Services 3.0 are also available in Office
SharePoint Server 2007.

However, Office SharePoint Server 2007 offers enhanced and additional
features that are unavailable on a Windows SharePoint Services site. For
example, both Office SharePoint Server 2007 and Windows SharePoint Services
include site templates for collaborating with colleagues and setting up
meetings. However, Office SharePoint Server 2007 includes a number of
additional site templates that are related to enterprise and publishing
scenarios. Similarly, Office SharePoint Server 2007 enhances the search
technology from Windows SharePoint Services 3.0 to include features that are
useful for employees in large organizations, such as the ability to search
for business data in SAP, Siebel, and other business applications.

Office Forms Server 2007

Office Forms Server 2007 is a new server offering in the Microsoft Office
system. It is a standalone server that delivers new Microsoft Office InfoPath
Forms Services, which is also available in Microsoft Office SharePoint Server
2007. This new technology uses server-based electronic forms to streamline
business processes and make data collection, distribution, and integration
more cost-effective than with paper-based forms.