European music works, baroque, classical, romantic and modern, how to distinguish them?

To put it simply, the western classical music school follows the rules of classical music to create works, while the romantic music school follows the author's mood at that time and writes how to better express the author's mood, without considering so many rules of classical music. Therefore, when we listen to the music of the romantic music school, we will feel that the conflict of musical emotions is very strong, and a soft melody may suddenly lead to a very passionate melody. There is a big emotional gap.