Common Blue Damselfly

There are many differences, but there are a few that you can keep in mind that will generally differentiate the two. Dragonflies commonly have large thoraxes and legs, and have broad wings. Damselflies generally have more dainty wings (they are not as powerful for flight), very thin abdomens and are considerably smaller in overall size! Hope that helps :)

What's the difference between damselflies and dragonflies?

This is a damselfly