Under the hood, the MacBook Air and Surface Pro 3 have a lot of the same hardware. Both feature Core i5 or i7 processors, 128GB of flash storage, and up to 8GB of RAM. The MacBook Air is packing a pair of USB three ports, a Thunderbolt port, and a full-sized SDXC port. The Surface Pro 3 has a single USB 3.0 port, mini DisplayPort, and a microSD card slot, making the MacBook Air a bit more functional.
Display the visuals
Microsoft stuffed a 21601440 resolution display into the Surface Pro 3. In a 12-inch device, the resolution makes everything look fantastic. By comparison, Apple's MacBook Air only has a Non-Retina,1440900 display. However, the high resolution comes at a significant battery cost. The MacBook Air is one of the few machines that can deliver more than 10 hours of battery life. Microsoft products just do not compare, especially when performing resource-intensive tasks.
Touch the difference
While the OS X does not support touch input, the Surface Pro 3 does. Having touched and pen input on the Surface Pro 3 the game breaker. If you plan to use your laptop only AS a laptop, the MacBook Air is fine. For anything else the Surface Pro 3 offers a superior overall experience. The pen input is either a big deal or something you'll never use. But for those who love drawing or handwriting, the Surface Pro 3 is unlike anything else on the market today.
Which is better?
As always, the answer depends upon your needs. If you need the best battery life, the MacBook Air is awesome. But if you want to fully enjoy the maximum in mobility and don't mind the decrease in battery life, you're likely to get a lot more out of the Surface Pro 3. While there is always room for improvement, Microsoft really knocked one out of the park with this version.