The g2s' are more akin to the
remo ambassadors. Pinstripes are more like
evans ec2s'or hydraulic. I haven't tried
aquarian myself, but I'm pretty sure they're more expensive.
Ec2s' are a more focused (dulled) sound than the g2's.
The g2 is 2 layers of mylar.
The Ec2 is also a double ply with a form of dampening ring around it.
Ambassador is two ply with hydraulic fluid in between this makes the sound more focussed than g2.
The Pinstripes are the same but with a third ring of mylar around the inside of the head for even more focussing.
Coating is a less offensive way of focussing the sound which is why a lot of drummers prefer coated g2 to Ec2.
Go to this site
http://evansdrumheads.com/EVAProductsDS.aspx?ID=13 where you can compare the
evans range and look into how they get their sound. This can help you with the other brands too.