
2013:
Boring style.
Monotone graphics. Everything looks the same.
Hard to read.
Drap colours.
No depth.
All kinds of shaders to help give depth to the place.
2015:
Way more readable due to better contrast, colour separation, use of colour.
Real depth due to building design. Shadows.
Way more texture diversity.
Backgrounds are set apart from the foreground.
Main character pop-out from the environment way more.
All in all: very good adjustments.