I just saw a picture from a friends Polaroid Instant Camera or Fujifilm Instax, and even when it is freshly developed (no aging or anything) the pictures have a distinctive "look", like a sepia effect with color, with the slightly off white balance. I was wondering, what causes the specific look both in the chemistry of the film, construction of the camera, and the optics?
Here is an example by Mrnerd1billion made by Ryan Notch of www.areographers.com - Own work, CC BY 3.0
I know that the low element lens might cause aberrations that cause the pictures to look nostalgic, but what are the technical differences in the instant films cameras that cause the pictures to look different from a standard disposable film camera or even SLR film camera?