one is greener than the other from the edge? I figure starfire should be relatively clear top down at 24", but across 48 may be tough to tell the difference.
It also depends on the thickness of the glass. Less than 1/2" thick you would be hard pressed to tell the difference (I know, I bought a tank with 3/8" front panel starphire, sides are regular, and it looks identical). Once you get above 1/2" thick the difference becomes much more noticeable.
I've got two identical 40L tanks, one is standard and the other is front/sides using starfire. Personally, I can tell a difference when looking at the tank from angles.. not through edges, just from angles. Looking at it dead on, I couldn't tell a difference. Corners are definitely cleaner looking.
They are blue from the side, not green. Also, put a piece of paper on on side, and look through it. If the paper has a greenish tint, the glass is regular plate glass.
You'll see the difference when the glass is clean. As far as the edges yeah low iron glass does have more of a bluish tint, but the glass is much more clear when filled and you have eye candy to view. Its worth every penny even at 3/8" thick.