Sequelize: difference of DataTypes and Sequelize

Question

I have seen the use of both classes for defining data types, including in the official documentation, both apparently serve the same purpose.

On a tutorial, I saw the application was using DataTypes for the Model and Sequelize for Migrations, you can exchange between them and they continue to work. Example codes:

Model using DataTypes:

module.exports = (sequelize, DataTypes) => {
    const Driver = sequelize.define('Driver', {
    firstName: {
      type: DataTypes.STRING(50),
      allowNull: false
    },

Migration using Sequelize:

module.exports = {
  up: (queryInterface, Sequelize) => {
    return queryInterface.createTable('Drivers', {
      id: {
        allowNull: false,
        autoIncrement: true,
        primaryKey: true,
        type: Sequelize.INTEGER
      },

Answer 1

The second parameter in both of them is just the sequelize package itself

const Sequelize = require('sequelize');

You'll notice in your index.js of models (if you set up as suggested) that you do something like the below, where you are passing in sequelize as the second argument.

const model = require(path.join(__dirname, file))(sequelize, Sequelize);

This exposes the data types. It doesn't matter what you call it. For example

  module.exports = (sequelize, asd) => {
    const Driver = sequelize.define('Driver', {
    firstName: {
      type: asd.STRING(50),
      allowNull: false
    },

Same with migrations.