What's the difference between a cliff and a tablet in calligraphy? Why is Zhang Qianbei called a monument and Ode to Shimen called a cliff?

The words of eulogy, biography and chronicle are first stippled on both sides of the ink knife and copied on the stone to form "hollow words", or directly written on the stone with red pigment, that is, the book is written on the stone and then engraved in the memorial place, which is called "monument". The words on the ancient tablet were written by famous calligraphers and masters, and the handwriting can be taken by later generations. Hammer the words on the tablet with tissue paper and Jiao Mo, and then mount them, which is called "rubbings", commonly known as "tablets". Cliff stone carvings can be divided into broad sense and narrow sense. Cliff stone carvings in a broad sense refer to everything that people carve on natural stone walls, including all kinds of stone carvings and stone carvings mentioned above, and a special kind of stone carvings-rock paintings can also be classified as cliff stone carvings. Cliff stone carving in a narrow sense refers to the literal stone carving, that is, using natural stone walls to carve notes. Cliff stone carving is an ancient stone carving art in China, which refers to calligraphy, statues or rock paintings carved on cliff walls. Cliff stone carvings originated in ancient times, and as a way of recording, they prevailed in the Northern Dynasties until the Sui, Tang, Song and Yuan Dynasties. Cliff stone carvings have rich historical connotations and values. ?