All photos where taken with the app VSCO Cam. Whit this app i have really discovered iPhone and mobile photography for me. Of course i have tried Instagram but I like the app and filters in this one much more.
On the side of photo content quality, there is a huge difference too. You could compare those two apps withe the video sites YouTube and Vimeo. YouTube is great but has also a lot of crap content. On Vimeo you would find more high quality videos that have this little extra to offer, just like VSCO Cam.
Go and have a look for yourself at http://vsco.co/ and find my VSCO grid http://niller.vsco.co/.