1. Cao is a member of China Calligraphy Association, and his calligraphy works have high value in the market. Zhao Dengshan is not an expert in calligraphy, so his works have no collection value.
2. Cao's works have depth, and there is room for appreciation in the future, which is worth collecting. Zhao Dengshan's calligraphy works are only personal hobbies and cannot be collected.