First of all, "drama" is not a very good translation, and it is easy for Chinese users to mistake it for "speech". In fact, the development of plot and emotion in drama depends on performance, not speech, and language expression is only a part of performance. Due to the improvement of stage technology, modern drama is a comprehensive performing art, not only relying on actors' performances, but also lighting, sound effects, beautiful props and even multimedia equipment. However, "musical" is by no means as simple as "drama+music". The reason why musical can become an independent drama is closely related to the closeness of music's participation in performance. As I said before, drama depends on performance, but most of the performances of drama are carried out through reading lines, limbs and conflicts. Musicals, on the other hand, add the element of music in this respect. The music here includes both singing, dancing and playing. Moreover, these music performances are not used as the background music of the stage scene to set off the atmosphere, but instead of traditional drama performances such as chanting, to directly shape characters, tell stories and convey emotions. For example, a common saying in the musical industry is: Why sing? Because the emotions you want to convey are not enough to be expressed by chanting; Then why dance? Because the emotions you want to convey are not enough to be expressed by voice letters. This is just like the expression of ordinary people. If you can't speak clearly, you should use poetry, a language expression with a sense of rhythm besides basic pronunciation. If the emotion intensifies again, it may be impossible to explain it in words, nor can it be sung. You can only rely on intense physical movements to relieve your feelings.

Therefore, when a drama is performed, one or two songs are added, and the songs are only used as the background to cooperate with the actors on the stage, instead of directly participating in the development of the plot, it can't be said to be a musical, just a "musical drama".