Though many predicted a smaller tablet out of Redmond at Tuesday's event, Microsoft went in the opposite direction, unveiling an even bigger Surface tablet. Dubbed the Surface Pro 3, Microsoft once again shoehorns ultrabook-class components into a relatively thin and light touch-screen slate. The new 12-inch Surface Pro 3 was made to replace your laptop and your tablet with one sleek, work-ready device. And despite divergent target markets and purposes, the comparisons with Apple's iPad Air($389.99 at eBay) are inevitable. So how do the two stack up? Read on for a side by side breakdown.

Since these two devices are so different in nearly every way, let's start with the one area they share some common ground: design. They're both essentially slick, metal-clad tablets, but they fight in two completely different weight classes. With its 12-inch screen, the Surface Pro 3 (11.5 x 7.93 x 0.36 inches) is considerably larger than the iPad Air (9.4 x 6.6 x 0.29). It's also more than 75 percent heavier at 1.76 pounds to the iPad Air's 1 pound flat. That's going to make a big difference for handheld use, as most tablets come in at under 1.5 pounds.

Microsoft's new tablet sports a 2,160-by-1,440-pixel display, which is close to the iPad Air's 2,048-by-1,536-pixel display in pure pixel count, but the bigger display on the Surface Pro 3 means a lower pixel density (216 ppi vs. 264 ppi). That's still pretty close, though, and initial impressions indicate that Microsoft has another solid display on the Surface Pro 3.

Beyond physical design and display, there really isn't a lot of commonality between the Surface Pro 3 and iPad Air. The former uses an x86, ultrabook-class chip from Intel (Core i3, i5, and i7), while the latter uses a custom ARM-based chip (Apple A7). Both use 64-bit architecture, but they're completely different beasts. The two utilize completely different operating systems. The Surface Pro 3 will run a full version of Windows 8, which can run all the familiar desktop and legacy applications on which Windows users rely. The iPad Air runs iOS and benefits from the most robust selection of tablet-specific apps around.

At every turn, it's clear that the Surface Pro 3 is meant for mobile productivity and getting real work done. And while you can certainly make a case for the iPad Air as a productivity device, you'll likely have to make some sacrifices to get the job done. They're designed with different purposes in mind, so whichever is best for you really depends on why you need a tablet. Think the Surface Pro 3 will replace your ultrabook and your tablet? Let us know why in the comments below.

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