It is traditional to describe it as being a kind of manure , if it is used this way. Green manures, while still alive and growing, may be turned directly into the soil, to improve the soil and add nutrients to it, or may be cut down, or pulled out, and composted elsewhere. However animal excrement is only one kind of manure. See the definition of manure. So by now you should know that the terms manure, and animal excrement used to improve soil, are not synonymous.
Animal excrement is only one of the various materials that are used manurially.
Shit adds off-flavors It has long been observered that the soil that plants are grown in affects the flavor of the plants, and that to some extent, the aroma and flavor of certain soil additives can be smelled or tasted, to a certain extent, when the plant grown in that soil is eaten. Many farmers have asserted that soil treated with cow excrement produces plants which tastes better than soil treated with chicken excrement. And this assertion is not generally challenged by anyone who has performed taste tests. Most people can taste the faint, but distinct echo of chicken manure, in the flavor of plants that have been grown in soil treated with a lot of chicken manure. The flavor can depend upon the kind of green manures used.