First look: Apple's new 11 and 13 inch Thunderbolt MacBook Air
In other respects, the 11 and 13 inch MacBook Air models haven't changed a lot, with the lighter, smaller model offering a few weaker aspects than its larger 13 inch sibling: a slightly slower CPU, smaller SSD options, and a lower resolution screen. However, the 11 inch model packs a resolution that is roughly the same as the existing 13 inch MacBook and MacBook Pro: 1366x768 vs their conventional "13 inch resolution" of 1280x800. Additionally, Apple now lets users who opt for the smaller form factor to select custom options that provide the same high end Core i7 processor, 4GB of RAM, and 256GB SSD options available for the larger 13 inch model. Last year, the 11 inch Air was limited to a lower speed CPU and maxed out at a 128 GB SSD, forcing buyers to choose between performance and size.
The 13 inch model still exclusively offers a larger screen of course, boasting a "15 inch resolution" of 1440x900, the same as the 15 inch MacBook Pro, packed into its 13.3 inch display (although the latest 15 inch MacBook Pro now offers a higher resolution, 1680x1050 option).
This makes the 13 inch MacBook Air very competitive with the entry level MacBook and 13" MacBook Pro and a good general purpose notebook machine, although it lacks fast Ethernet (it's intended primarily for use on wireless networks, and uses the same, separately sold 10/100 Ethernet dongle as the previous MacBook Air).
Both Airs also have no FireWire, no optical drive, supply less disk storage (due to exclusively using a fast SSD) and RAM (many Air models ship with a paltry 2GB, and they can only be upgraded as a build to order option for a max of 4GB; you can't add RAM after your initial purchase, as the memory chips are soldered into the logic board. Most other MacBook models can now accommodate a max of 8GB.)
However, with Apple's new adoption of Intel's Thunderbolt technology, which essentially makes a processor-direct PCI Express interface available externally, MacBook Air users can now plug their light, highly mobile notebooks into a device like the company's new Thunderbolt Display, which provides additional USB, Firewire, Thunderbolt and Gigabit Ethernet ports via a single Thunderbolt connection to the notebook. This opens up the thin and light Air category to a wider class of users who would otherwise need to buy a MacBook Pro just for connectivity.
The only obvious physical difference presented by the Thunderbolt port is that the MiniDisplay Port jack now has a Thunderbolt icon next to it. Other interfaces are identical to the previous model year's MacBook Airs.
This added connectivity for the MacBook Air also helps further differentiate it from the iPad, which sports a screen similar to the 11 inch Air while lacking its keyboard. With Thunderbolt, the Air is firmly positioned in a more powerful, flexible tier of computing than the handheld iPad (shown below next to the 11 inch Air and also between the 13 and 11 inch Air.
On page 3 of 3: Unboxing the Thunderbolt Air.