Cocoon and pupa are different in their ways of production and functions. Cocoon is the shell to protect larvae, and pupa is the transitional stage of insects from larvae to adults. Cocoons are usually made by insects such as silkworms and bees.

　　Cocoon and pupa are both stages in the development of insects, but they have different characteristics and functions.

　　Cocoon is a structure made by many insect larvae. Its main purpose is to protect and isolate the larvae. Before entering the cocoon stage, the larvae will secrete filamentous substances and gradually weave into cocoons around themselves, and then become adults in the cocoons. Different types of insects will produce cocoons with different shapes, sizes and materials to meet the needs of their own environment.

　　Pupa is a physiological state in which insects live. Before entering the pupa stage, insects such as butterflies and dragonflies have experienced three stages of growth and development: egg, larva and pupa. When entering the pupa stage, the larva will stop eating and completely transform its body to adapt to the new life after becoming an adult. In the process, a shell is generated to wrap it. This shell can take many forms, such as coffin form, bud shape and so on.

　　To sum up, cocoons and pupae are different stages and physiological states in the development of insects. Cocoons mainly play the role of protection and isolation, while pupae enter a new stage after larvae, and begin to completely transform their bodies.

　　Cocoon and pupa are the manifestations of different physiological stages in insect development.

　　Cocoon is a fibrous shell used by larvae before and after, which is usually woven by filamentous substances secreted by larvae (cocoon) or leaves and branches of plants. In the cocoon, the larvae will form adults, and the interior of the cocoon can provide protection and suitable environment to help the larvae complete smoothly.

　　Pupa is the stage of insect development to the last larval stage (pupal stage), in which larvae will progress to adults. Pupa is usually similar in appearance to adults, but has no mature sexual organs and wings. In the pupal stage, in most cases, the body structure of larvae will be completely changed, and the internal organs will also undergo great changes to adapt to the lifestyle and ecological environment of adults.

　　Therefore, the difference between cocoon and pupa is that cocoon is the fixed shell used by larvae before and after, while pupa is the physiological stage of the last larval stage, which represents the transformation from larvae to adults.

　　1. The difference between pupa and cocoon: cocoon refers to a layer of membrane wrapped outside the pupa, which is a bag-shaped shell used to protect the pupa. For example, cocoon is a shell formed by silkworm spinning; Pupa refers to the body shape of the whole insect when it is in the transition from larva to adult, and it is in the state between larva and adult. In this state, the insect can't move, but the inside of the insect is slowly changing. After a certain period of time, it will break out of the pupa.

　　For example, a butterfly, the caterpillar is its larval stage. After a period of time, the caterpillar will enter the pupal stage, waiting for the time to break the pupa, and after breaking the pupa, it will become a beautiful butterfly.