When you first spot a member of the Lepidoptera grouping, you will notice that the wings are either lying flat or folded together in a vertical position over the body. The insects with the flat wings are moths. They generally rest with the wings spread over the body in the flat position. Butterflies, however, rest with their wings folded together.
If you look more closely at a moth, you will notice that the antennae are feathered or fuzzy looking. This is because the moth uses the antennae to find food and to find a mate at night. The antennae provide a large surface area for the moth to intake scents on the air and locate things without light. Butterflies have antennae that are very thin with a slight widening at the tip. They also use their antennae for scent, and also for balancing in flight, but they are generally about during the day and find their food in brightly colored flowers. Because butterflies are out and about during the day, they identify their prospective mate by the coloring on the top side of the wings.
Because moths move about at night, they are more dully colored than butterflies. Their coloring does not play a role in finding a mate. Moths are highly scented with pheromones which allow them to find each other at night. The dull coloring allows the moths to rest quietly during the day without being readily noticed by predators. Brightly colored butterflies rest at night when their coloring does not make them noticeable.
Both butterflies and moths have scales, which assist them in flying. The moth, however, has a thicker covering of scales. These scales are so thick that many moths take on a furry appearance. The thick covering of scales protect the moths from the heat and damage of the sun when they are sleeping during the day. This is one of the reasons they sleep with their wings spread flat.
Moths use camouflage to protect themselves while sleeping. The dark markings on the spread wings resemble eyes. This is a protective marking that will make a predator think the moth is a different sort of creature with a larger head and eyes. Butterflies also use camouflage. The most famous example of butterfly camouflage is the viceroy butterfly which uses similar markings to protect itself from the predators of the poisonous monarch butterfly. A wise predator will think twice before tasting the viceroy to determine whether it is a monarch or not.