What's the difference between herbs and materia medica?

Herbs mainly have two meanings: first, they have grasslike or fleshy stems, the xylem is underdeveloped, and most of the aboveground parts are larger than the withered plants that year. But there are also biennial or perennial evergreen trees with developed underground stems. The second refers to manuscripts.

Herbs are the general name of a kind of plants, but they are not a unit in the scientific classification of plants. The concept corresponding to herbaceous plants is woody plants. People usually call herbs "grass" and woody plants "trees".

Another way of saying Chinese herbal medicine in materia medica. In ancient times, there were many works about Chinese herbal medicine named after materia medica, such as:

Shennong Materia Medica Classic, Wupu Materia Medica Classic, Notes on Materia Medica Classic, Newly Edited Materia Medica, Dietotherapy Materia Medica, Haiyao Materia Medica, Materia Medica Illustration, Materia Medica Extension, Decoction Materia Medica, Southern Yunnan Materia Medica, Finished Materia Medica Collection, Essential Materia Medica, Mongolian Materia Medica, Elegant Materia Medica, Semi-finished Materia Medica, Required Materia Medica, Newly Edited Materia Medica, Fried Materia Medica.