Ultrabooks are redefining what laptops should be. They are not just notebooks but they blur the lines between major computing devices like personal computers, tablets and laptops.

Two of the most popular and best reviewed ultrabooks today are Lenovo's IdeadPad Yoga 2 Pro and Sony's Vaio line series. As of the best, which is the better option?

Lenovo IdeaPad Yoga 2 Pro

Lenovo's IdeaPad Yoga is one of the best hybrids around demonstrating how laptops and tablets should be combined. The device runs on Windows 8 and sports a 13-inch display. Lenovo also released a similar 11-inch laptop and both models are considered among the most successful type of Win 8 multimode devices. Microsoft, Best Buy and similar brands have endorsed the products.

The original model was already much-loved. Is there a way to top this? Yes, the second generation Yoga does it even better. The Yoga 2 Pro features a extremely high resolution 13.3-inch display. It offers 3200 x 1800 pixel resolution.

The resolution makes Lenovo a contender against MacBook's Retina Pro, Toshiba's Kirabook, Samsung's Ativ Book 9 Plus and ChromeBook Pixel among others.

This is an extreme improvement since the original model only offered 1600 x 900 pixel support. It is the same thing found on Lenovo's 20-inch Flex 20. The Yoga 2 Pro is also lighter and thinner. It only measures 15.5mm and weighs 3 pounds.

The backlit keyboard is also something worth noting. Several sources commend Lenovo for putting out an improved keyboard. This makes the Yoga 2 Pro one of the best-looking and functional ultrabooks. The device hits stores this October.

Sony Vaio Flip PC

Sony's Vaio Fit is a Windows 8 powerhouse. Users can choose either a standard Windows 8 or the Pre version. The series also runs on Intel Haswell Core i7-4500U processor. The line also features 16GB of DDR3 RAM. People can choose among a number of hard drive combinations: up to 1TB hybrid or 512 GB SSD.

The Vaio Flip multi-windows is available in 13 , 14 and 15-inch models. All come with a digitizer pen for better use. Vaio Flip models have Full HD screen while the 15-inch variation sports an impressive 2880 x 1620 Triluminous display. Describing it as stunning is an understatement for the display. As a bonus, Sony provides users with two options for the graphics: Nvidia GeForce GT 735M or integrated Intel HD Graphics 4400.

Connectivity options include HDMI, USB 3.0, Bluetooth and Ethernet.