What ORM is

ORM is a library which allows to work with relational databases in object-oriented languages.

TypeORM

Implements data mapper pattern: model object doesn't know about persistance and has data fields and business logic. Repositories are used for CRUD operations.

Sequelize

Follows active record pattern: model object has data fields, business logic and database CRUD functions.

Prisma

Query builder. Generates data types from a schema definition. Uses typed functions almost everywhere. Prisma objects have only data, there is no behavior. Almost no raw queries.