I watched some videos. What's the difference between hand dance and sign language?

Because sign language is a bridge between deaf people and society, in order to express meaning, typing sign language will type out all the important words in the words; Hand language dance is the key word of each lyric, not every word, which is more concise and most of the movements are slow and elegant. The above is my simple view on sign language after I learned it. I hope I can help you.