[rootusrootus]

That's a stretch. To begin with, you can't even see the blue/green difference until you actually send a message to someone. All received messages are gray. And even without the color, you instantly know the difference between the two -- one tells you it was delivered, the other one is a shot into the void.

[Jcowell]

No you can detect if a number is iMessage by putting it in the sender tab of a message. If it’s iMessage-able then it will turn blue.