Roughly speaking, flavor profiles from Briess' website...
Lighter crystal malts (20L)- "Candy-like sweetness, mild caramel"
Light-medium crystal malts produce (40L) - "Sweet, caramel, toffee"
Medium crystal malts (60L) - "Sweet, pronounced caramel"
Dark-medium crystal malts (80L) - "Pronounced caramel, slight burnt sugar, raisiny"
Dark crystal malts (120L) - "Pronounced caramel, burnt sugar, raisiny, prunes"
As mentioned, while the blending of crystal malts may lead to the same beer color, the flavors within the crystals malts will still come through. Using 160L crystal which is very dark, so your numbers may be EBC, will impart raisiny, burnt sugar, flavors in your beer despite blending it with 20L.