OEM (Original Equipment Manufacturer) versions are specifically designed for a particular computer like a Dell Inspiron 6000. This version is primarily used by major computer companies and has specific drivers and applications that enable it to function correctly. You may be able to use this if you know how to custom build the operating system. The OEM contains an application that customizes the XP install process and builds an ISO.
The retail, however, is like a general operating system designed to work with most computer configurations. It has drivers that support most of the hardware used today.