1. Scale: A first-class library usually has a large building area and can provide more reading space and seats to meet the needs of more readers. The building area of the auxiliary library is relatively small, which can't accommodate a large number of readers to read at the same time.

1. Resources: The number of books in first-class libraries is usually more than 5,000, which means that readers can find more kinds of books in first-class libraries to meet more diverse reading needs. However, the number of books in secondary libraries is relatively small, which can not meet the needs of readers in some professional fields or popular books.

3. Perfect facilities: First-class libraries are usually equipped with advanced facilities, such as automated management systems and digital resources, to provide readers with convenient borrowing and query services. The facilities of secondary libraries are relatively simple, which will affect the convenience of readers' borrowing and querying.