The Amazon Kindle and Apple's iPad are two very different devices. We compared both in all the relevant categories to see which you should build your digital library atop.

Kindle vs iPad: Readability

Winner: Amazon Kindle

The foundation of all e-readers prior to the iPad started with e-ink and for good reason: Nothing comes closer to the smooth, comfortable look of paper. While the iPad’s IPS LCD screen technically boasts better contrast, the Kindle manages an excellent approximation of newsprint, you can read it easily even in direct sunlight, and the lack of a 60Hz refresh rate makes it easier on the eyes over many hours.

Kindle vs iPad: Graphics

Winner: Apple iPad

As a drawback to all the Kindle’s newspaper-like qualities, it’s also cursed with graphics capability that makes the print version of USA Today look like a technological triumph. The reader offers just 16 shades of grey in comparison to the iPad, which boasts full color, not to mention the ability to refresh up to 60 times per second for fluid video. For magazines and interactive features, the Kindle truly can’t compare.

Kindle vs iPad: Portability

Winner: Amazon Kindle

We would take either of these devices compared to a sagging backpack full of books and magazines, but the Kindle has the iPad beat by a mile when you start counting specs. Measuring only 0.34 inches thick and weighing 8.7 ounces, the Kindle makes the 0.5-inch thick, 1.5-pound (24-ounce) iPad look and feel like an anvil.

Kindle vs iPad: Battery Life

Winner: Amazon Kindle

Apple’s iPad actually offers impressive 10-hour battery life, which is more than most folks will even be able to read in a sitting before tossing it back on the charger, but the Kindle can go days and weeks without a charge.

Kindle vs iPad: Library

Winner: Apple iPad

You could pile numbers to the ceiling comparing Apple’s iTunes book library to Amazon’s Kindle library, but the simple fact is this: The Kindle can only access Amazon’s library, the iPad can access Apple’s iTunes store, the Amazon Kindle store, Barnes & Noble’s Nook library, and more, all through apps. In an unusual twist, Apple actually has the more platform here, and until that changes, iPad owners have access to more printed content than any other e-reader can deliver.

Kindle vs iPad: Price

Winner: Amazon Kindle

Like comparing a motorcycle and a muscle car, comparing the Kindle to the iPad is unfair for a couple of reasons, but for most folks, the most glaring will be price. The Kindle now runs for only $139 for a Wi-Fi-only version, and $189 for a version with lifetime 3G access for downloading books on the go. The cheapest Wi-Fi iPad runs for $499, and adding 3G spikes that number to $629, plus data charges of at least $15 monthly from AT&T. The total price disparity after using a Kindle and an iPad for two years? $800.

Overall, both of them have their own strengths. Which one you want to get all depends what you want to do. Just choose the right one you need and enjoy your reading pleasure!