Ahh the classic clash between two brothers. In this case, we have two brothers of color, in that they are not on opposite ends of the spectrum in terms of likeness within the color universe, but rather they are brothers; similar, but very different.
When I see blue, I see immediate depth and personality. I see an everlasting surplus of blue depth; one that words could not begin to describe in terms of bounds or limits. There's a beauty about it that makes itself so obvious upon first glance, yet the beauty does not mutate into a false prophecy after a bit of observation. Blue is a consistent flow of immediate depth and beauty.
Green, on the other hand, is a different character. Upon first glance, green does not reveal its true character. Green is encapsulated by a bit of a "hard" shell, if you will. It takes more than a second to dissect the true beauty that lies within the color green. While green's depth and beauty aren't as detectable as those for blue, that in itself increases green's value. It's a privilege to have a color in which a bit of perception is required to reveal its clever mask.
Now, I think the difference between the two colors can be attributed to a real-life scenario. It's so incredibly simple, but I didn't realize how strong of a correlation the above comparison shares with this real-life scenario. Take water and grass. Water (blue), of course, contains an endless depth of blue which is evident immediately upon contact. Grass (green), on the other hand, doesn't reveal its true beauty at first. One must frolic and pick a few blades to really lock into green's true value.
Blue and green. BFF's.