Coenagrion puella is a damselfly rather than a dragonfly. As is typical of damselflies, the insect is slender, its fore- and hindwings are similar in size and shape, and when the insect is at rest, the wings are held back aligned along the abdomen.
There are more visible features to distinguish dragonflies from damselflies, one of which are the compound eyes. In dragonflies the eyes touch, or nearly touch, at the top of the head. The two domes of the eyes form an almost round head. In damselflies, the eyes are clearly separated, usually appearing at the sides of the dumbbell-shaped head.