A Mac serial number contains information including the order number, model number, EMC number, model identifier, actual serial number and Intel processor number. This information is all embedded within the full serial number for all Mac products.
Order numbers refer to a specific Mac configuration of hardware. By comparison, model numbers refer to a family of products such as MacBooks. This is further refined by the model identifier which identifies a particular product in the family, such as a MacBook 5.1. The EMC number is used to identify a hardware family. For example, EMC number 2254 refers to MacBooks using a "Core 2 Duo" processor, regardless of the processor's individual clock speed. To further refine this, the Intel processor number denotes which particular processor is in the computer. Finally, the serial number is the actual, unique machine serial number embedded in the larger serial number itself.