What's the difference between a chrysalis and a cocoon?

The words cocoon and chrysalis are often used interchangeably when talking about monarchs and other butterflies. However, they are two completely different things! Cocoons are specific to moths, while chrysalises are formed by butterflies. Moths spin silk around themselves and molt inside the silk casing. This provides extra warmth and protection from the surrounding environment. You can usually find cocoons attached to the side of something or buried underground or in leaf litter. 

Chrysalises, on the other hand, are not silk. Butterflies molt into a chrysalis, which is a hard exoskeleton covering that protects the developing butterfly beneath. Chrysalises are typicall found hanging from something. For example, monarchs spin a small silk button from which to hang upsidedown before molting from head to abdomen!