I don't know about blue side but in many of the older store different sections are painted different colors (groceries - green, home decor - blue, ).
Even though our store has been remodeled and painted all red many of us still refer to blue world, red world, and green world.
Also, former greatland stores (non-superT stores with two entrances) have blue doors and green doors. Greenworld is pharmacy, food ave, hba, ppc, market, pfresh, seasonal and domestics. Blueworld is guest service, photo, see spot save, electronics/mmb, stat, sport, office, small app, home decor, furniture, toys and automotive. This might vary on a store-to-store basis, but generally you'll have 1 HLTL in blue and 1 in green, as well as your CTL supporting the pfresh/market side of green.
We were a P01 store, renovated in 2007/2008. All walls are now red, except for the entrances with still keep the green/blue paint.