Why are block letters and hard pens different in China's calligraphy? Can you write in block letters with a brush? Beginners don't understand, please advise.

Brush and hard pen are two different things, and the font pits written are different. Because the brush is made of animal hair and can absorb a lot of ink, the words written are divided into five colors, dry and wet, which are very charming. Hard pens (rigid pens, ballpoint pens, pencils) can only write external forms, but they can't write charm. So they are different.

You must learn from the ancients when writing brush strokes. Your post has a high starting point, and the level of writing will be high. For example, any one of Lin Kai Liu Gongquan, Yan Zhenqing, Chu Suiliang and Zhao Mengfu is the best example for us to learn from. Wang Xizhi's running script, Mi Fei's running script, Wen Zhiming's running script and Wang Duo's running script are all good examples for us to learn. It's best not to create your own fonts, which will get worse and worse.