How can I identify an orb spider?

Question

They all look the same to me! Is there some defining characteristic on the spider that makes it an orb spider or do I need to see its web to tell what it is?

Answer 1

Shape of the body, spinets and colouring, but web construction is important.

Answer 2

Learn to ID it with the help of these sites -

http://bugguide.net/node/view/1954

http://www.arachnology.be/pages/Pictures...

http://www.spideridentification.org/