Therefore, writing with a brush is not necessarily good. (But most practitioners know the importance of font structure to Chinese characters. So the writing brush is good, and the pen is not too bad. )
Pen can copy software characters, but mainly copy font structure.
The same font and font, written with pen and brush, are mainly different in content created by lines. A brush has more room for change on paper, while a pen is smaller. If you don't have a good command of calligraphy before, you'd better start with official script, which is easier to master. For beginners, Cao Quanbei is a good copybook for beginners to practice. Don't write regular script until you master and skillfully use the brush.