Go to the everymac.com web site and look up specifications for the Air. It kind of depends upon you as a user. The MBA is going to be newer and will see more years before it gets left behind in Apple's endless upgrade releases (every year now it seems). The MBA will likely also be easier on batteries, and lighter overall. On the other hand if you like connectivity and being able to upgrade your computer the MBA is not that with everything soldered in place and limited ports.
Are you sure the MBP has a 480 GB SSD (not HDD)? I don't know if it is at all possible even through third parties to upgrade to a SSD that size in a MBA. If you needed to it would still cost a fortune.
8GB RAM is enough for most purposes and Apple doesn't seem to be doing the big jump in RAM use with each OS release the way it used to. We can't predict what they will do but at least for now 8 GB seems to be "okay".
You know, I think about your 2012 and I think it is the kind of computer somebody like me might go for. Starting to get a tiny bit old but probably will make it through another couple of OS releases by Apple. Even then a computer is still usable with an older OS for another 5 years or so, so the thing probably has another 8 years left in it even unless you are an absolute must have the newest features. I would like all the ports in the 2012 and that it could be upgraded in RAM to more than the MBA has now and probably even have both a SSD and a conventional hard drive for more room (not sure about the exact specs. of the 2012 MBP). I don't mind a bit of extra weight. I don't know about the relative resale values of the two machines (check places such as e-bay, factoring in details) but I would see the MBP as something for me I could sink another $100-$200 and keep it for another 8 years and it would have the features I would not find in a MBA. Again this is all from what I like in a computer and you have to decide what is important for you.
