Both are good choices in their own right, it's going to come down to personal preference. The first thing you will notice is that Vaio Pro is much lighter. It is really night and day. The Vaio Pro has a far superior display. Much better contrast ratio, much wider colour gamut and better accuracy, much wider viewing angles, not to mention higher resolution. It has a more durable build, slightly faster CPU and SSD, more configuration options (the big deal being 8GB RAM). Finally, the real biggie - touchscreen. Macbook Air has much better battery life and touchpad, slightly faster GPU. Do note however that Vaio Pro has a sheet battery option and even with that it is lighter than Air, and battery life would be in the 15 hour range. Pricing is pretty similar for the similarly specced option.
Those are the objective variables. Coming to the subjective personal preferences - the big ones is the construction. Technically, Vaio Pro wins here, but carbon fibre brings an inherent flex which gives the perception that Air with its aluminium would be more durable. So it is really personal preference, but I would choose carbon fibre any day. Vaio Pro keyboard has slightly better response and click, while Macbook Air has slightly deeper travel. My personal choice would be Macbook Air but it is very close. Then of course is the eternal OS X vs Windows which is again your choice. OS X users would say stick with OS X, Windows users will say stick with Windows, ultimately you have to decide based on your usage. One thing I will point out though is that Windows 8 with touchscreen is a fabulous, game-changing experience for a lot of usage scenario, and 8.1 makes it better still. Once you go touch, there's no going back. I think ultimately it comes down to a simple thing - if you use OS X get a Macbook Air, if you use Windows get Vaio Pro.
Personally, I would wait for devices like Ativ Book 9 Plus or Zenbook Infinity. Those appear to be superior, cutting edge options than either of the above. Or Haswell Macbook Pro with Retina Display 13 if you want OS X.
PS: The other Haswell ultrabook shipping in the US now is Acer S7, which could be a great choice too. Some variants are said to ship with a 2560x1440 display, but no idea when it releases in India. Then there's also the Vaio Duo 13, which is a convertible slider. I think these are all the Haswell ultrabooks as of now?