Although there are many different kinds of dragonflies, in Ohio, they all belong to one of two groups (superfamilies).
These can be seperated by wing vein patterns.
The Skimmers (Libellulooidea)
The wing 'triangles' are different on the front wings than those on the back wings.
Antenodal cross-veins lineup in first two rows of the wing.
The Darners (Aeshnoidea)
The wing 'triangles' are similar on the front wings and the back wings.
The antenodal cross-veins in first two rows of the wing do not quite line up.
In this illustration, look closely at the second row of cells that are slightly tinted to see the cross-veins misaligned with the row of cells on the leading edge of the wing.