Determining which model of the MacBook Pro you have can be a challenge. The same model numbers can have a variety of processor configurations.
The MacBook Pro laptop was first introduced in January 2006; it replaced the PowerBook G4, Apple's earlier professional line of laptops. The original MacBook Pro model came in an aluminum enclosure, a trend that continues with this line of laptops today.
After more than two years and numerous incremental upgrades, Apple announced a completely new MacBook Pro model in October 2008, dubbed the MacBook Pro 15" Unibody. The MacBook 15" Unibody is a distinct update of the original MacBook Pro, packing all the previous features of the Pro into a more stylish and lighter weight aluminum enclosure.