Cocoons and chrysalises are terms that are used during the developmental stages of insects like butterflies and moths. These insects have four different stages of development, and Cocoons and chrysalises are terms used to explain some things about the developmental stages of butterflies.
Cocoon is the silky protective case produced by the larvae of some insects like butterflies to act as a guard and protect the insect during the pupa stage of development. Chrysalis, on the other hand, is another term which can be used for the pupa stage of development in insects.
At the pupa stage, an insect is ready to develop fully into an adult stage. It comes in between the larvae stage and the adult stage. The silk material produced by the larvae is woven, and it is attached to a leaf and other things that can serve as protection for the insect at the pupa stage.