What is the meaning of the difference between heavy words in calligraphy?

In calligraphy, "different emphasis on words" means that there are the same words in the same calligraphy work, and the writing methods should be different.

For example, in Wang Xizhi's Preface to the Lanting Pavilion, there are 20 "zhi" characters, plus 1 a "zhi" word ***2 1 a "zhi", which are written in different ways and are almost the same, but each has a different attitude and aesthetic feeling.