Confused between tamron sp 70-300mm vc usd and nikon 55-300mm vr for d3100.any suggestion?

I have a nikon d3100 and now i'm planning to buy a zoom lens for it but i can't decide between nikkor af-s 55-300mm vr and tamron sp 70-300 vc usd. I know that first one is intended for dx sensor cameras like mine and 2nd one for fx, but works with dx too. How tamron performs on d3100? What pictures shows in exif about the lens? Like if i shoot with a nikkor 18-55mm lens the image shows about the lens.is it shows tamron? Whichone would be the best lens for it? Please help!

p.s - since i'm with tight budget, i can't afford nikkor 70-300 vr.

You shouldn't be confused. You can afford the Tamron but not the Nikon. You have no choice.

If you really want quality, save more. If you're in a hurry, buy the cheaper one. You should know by now that in photography, you get exactly what you pay for.