It can be said that hard pen calligraphy is pen calligraphy to a certain extent.
The writing of pen calligraphy, the characters are relatively small, and it is impossible to understand the stippling and structure of Chinese characters well.
Only brush calligraphy can enlarge Chinese characters and better observe the stippling and structural characteristics of Chinese characters.
Therefore, if you want to learn calligraphy well and understand the connotation of Chinese characters fundamentally, you can only learn brush calligraphy.