I took two photos, one with each camera app. Their dimensions are the same; 2560x1440, the only difference I can see is that the Amaze image is double the filesize, but it certainly doesn't appear to be double the quality.
I'm using the 1920 version of the app because I couldn't run the larger one in 3D (I must have a newer handset with a smaller second camera sensor).
I'll keep the app on my phone but I'll mainly use the stock camera, aside from the UI there is precious little between them. On Amaze I can't access Image Adjustments or White Balance, so on the whole it's a little disappointing, especially as the guy who developed it is no longer working on it according to the start of his post.
To get the Image Adjustments and White Balance to work hit the A button in the right corner. You will see a menu pop up. Hit the M, manual button. There you will be able to change what you need.