Hard Drive
The principle difference between Xbox 360 consoles is the hard drive size. The Xbox 360 Pro originally came with a 20 GB hard drive, which was later replaced with a 60 GB hard drive. The Xbox 360 Elite originally came with a 120 GB hard drive, which was later replaced with a 250 GB hard drive. The larger hard drive size is only necessary for players that download a large number of videos and games to the hard drive. Normal game saves do not occupy that much hard drive room.
Appearance
One difference between the two consoles is the color of the system. The Xbox 360 Pro is a white console, identical to the Xbox Core and Xbox Arcade consoles. The Xbox 360 Elite is the only black console released by Microsoft. This is purely aesthetic and has no bearing on performance. These are the standard colors for the systems; in some cases the console might have been sold with a different color or appearance as part of a bundle.
System Performance
All of the Xbox 360 consoles have identical system specifications, excluding the hard drive size. Both the Xbox 360 Pro and Xbox 360 Elite can play games equally well. Both of these consoles are "backward compatible" with games for the original Xbox due to the presence of the hard drive. This is an advantage over the Xbox 360 Core and Xbox 360 Arcade systems which do not have hard drives.
Accessories Included
The accessories included with any Xbox 360 console can vary based on the year it was manufactured. Consoles sold as part of a bundle typically comes with a unique assortment of accessories and games, as well. Typically, most versions of the console come with the same basic items. This includes a wireless controller, headset, Ethernet cable, and video cable.
Price
The Xbox 360 Elite retailed for $299.99. The Xbox 360 Pro was discontinued, and is no longer sold new. Both systems can be bought refurbished or used. The exact price will vary based on the seller, but the Xbox 360 Pro will typically cost approximately $100 less than the Xbox 360 Elite for the same condition.