Mongoose is technically not an ORM (Object-Relational Mapper), but rather an ODM (Object-Document Mapper). Here's the difference:

• ORM (Object-Relational Mapper): Used with relational databases (like MySQL, PostgreSQL), an ORM maps objects in code to rows in tables. It uses relational data structures (tables, columns, and foreign keys).

• ODM (Object-Document Mapper): Used with document-based databases like MongoDB, an ODM maps objects to documents (usually in JSON-like format). MongoDB is a NoSQL database, and its data structure is more flexible than relational databases.

Mongoose is an ODM because it deals with MongoDB, which stores data in collections of documents rather than rows in tables. Mongoose provides a way to define schemas, interact with the database using JavaScript objects, and perform operations like queries, updates, and inserts in a more structured and abstracted way.