Wow! Thank you!! I am learning so much about these. You have helped tremendously on how to tell them apart.

This is a Great Spreadwing, one of the spreadwing group of damselflies. It's as long as many dragonflies, but belongs in the other branch of Odonata. The Great Spreadwings are easily distinguished from other local spreadwings by their size and that vivid yellow stripe on the side of the thorax.

Other damselflies fold their wings neatly over their backs, but the spreadwings "dangle" theirs loosely, as your image shows so clearly. Here is another spreadwing image: and one of the more typical damselfly pose:


Dragonflies are more robust, thicker-bodied and with thicker abdomens; often their eyes meet at the top of the head. They usually hold their wings out to the side, like little airplanes, or cock them down and forward. Here are two examples: with wings out flat and with wings cocked down and forward