Apple has debuted the iPad Air 2, the follow up to last year's iPad Air, and it's time to investigate what's new, what's not and whether an upgrade should be on this year's holiday list.

Here are the differences between the iPad Air and iPad Air 2.

Design

Last year, Apple promoted the iPad Air by comparing it with the width of a pencil. This year, Apple took that one step further by shaving off exactly 18 percent of that pencil. At 18 percent thinner, the width of the iPad Air 2 comes in at just 6.1 mm, less than half the width of the original iPad. The iPad Air 2 is the thinnest iPad in the world.

Apart from the thinness, users will also notice the addition of Apple's Touch ID technology. Touch ID was first added to Apple devices with last year's iPhone 5S and allows for both extra security and easy device access.

Camera

While the iPad is often not a user's first choice when it comes to taking photos, many still like to take the occasional snapshot with it. For those users, Apple has finally upped the camera to 8 megapixels instead of five. Things like aperture remain the same in the iPad Air 2.

On the software side, the iPad Air 2 now includes digital image stabilization, burst mode, Timelapse, slow motion capabilities and the ability to capture video at 120 frames per second.

Display

The display of the iPad Air 2 is not too different from the iPad Air. In fact, the resolution is the same at 2048 x 1536. Apple has, however, more tightly bonded the layers of glass in the display which help make the device lighter as well as probably thinner.

Performance

The processor of the iPad Air 2 is significantly faster than that of last year's iPad Air. In fact, Apple has reintroduced X series chips just for tablets. The A8X chip that's found on the iPad Air 2 is about 40 percent faster than the A7 found on the iPad Air, according to Apple.

Conclusion

The iPad Air 2 is certainly a better device than the iPad Air, but that doesn't mean it is necessarily worth spending extra money.

The Wi-Fi iPad Air 2 costs $499 for the 16-GB version, $599 for the 64-GB version and $699 for the 128-GB version. The original iPad Air currently costs $399 for the 16-GB version and $449 for the 32-GB version.

For those who really need a high-power device or expect to take photos with their iPad, then perhaps the iPad Air 2 is the better choice. If, however, you're just going to be watching YouTube videos and writing the occasional email, then perhaps save your money and go with last year's still-great iPad Air.