What is the difference between regular script and hard pen in calligraphy?

Regular script is a font of China's calligraphy, also known as regular script, which appeared in Wei, Jin, Southern and Northern Dynasties and reached the peak of its artistic life in the Tang Dynasty. At present, the most classic inscription is "Liu Zhao the tern", one of the four masters of regular script. Earlier calligraphers included Wang Xizhi, Wang Xianzhi, Zhong You, and Zhi Yong monk.

The ancient regular script works we saw were all written with a brush, or directly written on paper or cloth, or burned on ceramic utensils and engraved on stone tablets after writing. But later, hard writing tools such as pens, pencils and ballpoint pens appeared. We call regular script works written with this writing tool "hard pen calligraphy".

However, there is another view that the hard pen appeared before the writing brush, because before we invented the writing brush, our ancestors had carved marks on animal bones and stone walls with stones and knives. Since it is also a writing tool, it should belong to the category of hard pen.

Although this view has some truth, marks do not belong to calligraphy after all, so they do not belong to calligraphy tools.