1, with different abbreviations: EI is the abbreviation of EngineeringIndex, which is an engineering index. ER is the abbreviation of Entity-Relationship, and it is an entity relationship model.
2. Different concepts: EI is a comprehensive retrieval tool in the field of engineering technology, which helps engineers find related patents, papers, reports, technical standards, dynamic information, etc. ER is a model of database design, which helps designers to better understand the relationship between data in the real world and better design the database structure.