Different colour?
 

Are there different kinds of blue for the impreza?

Between wrx and wrx sti?

For example would this, http://i418.photobucket.com/albums/p...x/IMGP0920.jpg

Be the same colour as this, http://static.cargurus.com/images/si...pic-65495.jpeg

Reason asking is because I'd like to maybe change my normal wrx bumpers for sti ones

Yes there are different blues, there will also be different shades of the same colour so it's unlikely you won't get a perfect match, front bumpers are also prone to stone chips and other marks. Just budget in for a spray job,

You could buy the fog covers and winglets and use your own bumper. Any slight colour difference wouldn't be seen the same as a whole bumper. The paint codes should both be 02C. And you'll be ok.