1, meaning different: drilling old paper piles is to study ancient books; Eating the ancient is mechanically copying the old saying, that is, you can't thoroughly understand the ancient knowledge you have learned and can't absorb what has become your own.
2, the usage is different: drilling paper pile is usually used as predicate and object; Eating in the past is usually used as a predicate.
3, the source is different: the pile of drilling paper comes from "Bai Yang's Essays Turbulent World"; It's from Zhuangzi, a master of health preservation.