All kinds of life stay alive by using nature around them. All do activities for the purpose of using things found in nature for their own good. Plants take in water and sunlight. Animals eat plants or other animals. Of course, to use readymade materials of nature is not true work; work is an activity that changes these materials from their natural state to improve their usefulness. The bird, the bee, and the spider, in building nests, hives, and webs are all working. So both humans and animals work: they change nature to make it more fitting for their needs.
However, human work has important differences from the work of other animals. The work of the bird in building its nest shows more continual steady effort than most humans in their building plans. The work of the spider in making its web goes beyond the work of most human weavers. A bee's work is better than the building work of most human architects. But the biggest difference between the work of an architect and a bee, for example, is that the architect can picture in his mind a building before building it, while a bee cannot. At the end of every human work process, we get a result that already was in the mind of the worker before it was started. Human workers not only change the form of the material they work with but also know the purpose for their work, while animals do not.
Human work is conscious, while the work of other animals is instinctive. Instinctive activities are inborn rather than learned. Instinctive activities are part of a fixed pattern. For example, it has been seen that a spider which has finished half of its web will continue to make the second half even if the first half is taken away.