Which type of an atomic structure our bird wings and butterfly wings when compared to each other?

The wings of birds and wings of a butterfly, when compared to each other, can be illustrated as analogous structures.

In animals, analogous structures refer to those body compositions that are used to do identical activities, however, exhibit distinct evolutionary history. They are also known as convergent structures. The formation of these structures takes place as an outcome of the requirement for the animals to amend with the environmental conditions. For example, both the butterfly and bird use their wings for flying.