Lin means to write or draw according to the original work; imitation means to write or draw on top of the original work with thin paper (silk).
In the broad sense of copying, what is imitated is not necessarily calligraphy and painting, but may also be steles, calligraphy, etc. Copying focuses on the process of copying in order to learn techniques. Acquisition of reproductions for preservation, restoration, exhibition, and sale, focusing on the results of copying.
Lining and copying each have their own strengths and weaknesses. It is easy to learn strokes in Lin, but it is not easy to learn the frame structure; it is easy to learn the frame structure in G, but it is not easy to learn strokes. In terms of difficulty, it is easy to imitate but difficult to imitate. Regardless of copying or imitating, the goal must be to "resemblance" to the character Fan, and gradually transition from "similarity in form" to "resemblance in spirit".
Copying is an important means of learning calligraphy, especially in the beginner stage, where most of the time is spent on copying. There are also calligraphers who often copy in their later years, even throughout their lives. For example, Hu Xiaoshi and Lin Sanzhi still do daily copying in their later years; Zhao Mengfu and Wang Juesi still indulge in copying Wang Xizhi's calligraphy in their later years.
The copying we are talking about now generally refers to copying rather than copying. In fact, the so-called copying at that time included two different methods: copying and copying. Copying can also be divided into two methods: tracing and printing. Tracing red means copying on red words printed specifically for copying books; copying means covering copybooks with translucent paper to copy.
The "copying" method is generally only used by beginners, but it can also be used for further practice and research. From copying to writing, then from facing to back, and from back to thinking, this represents the progress and improvement of calligraphy learning. There is a saying of "three turns and nine returns" in spiritual practice, which means that true practice often requires going from low to high, and from high to low, repeated many times, so as to truly make the work practical and achieve perfection.