What are the different Composer package types in Magento 2?

Magento system uses Composer packages to distribute, install, and upgrade components in an application.

composer-magento

Table below shows all the package type used in the Magento.

Friendly namecomposer.json type
Metapackagemetapackage
Modulemagento2-module
Thememagento2-theme
Language packagemagento2-language

Sample composer.json from Magento system as follows :

Metapackage

Technically, a Composer package type, not a Magento component type. A metapackage consists of only a composer.json file that specifies a list of components and their dependencies. For example, both Magento Open Source and Magento Commerce are metapackages. (Reference Magento DevDocs)

Module Package

/vendor/magento/module-msrp/composer.json file for module

Theme Package

/vendor/magento/theme-frontend-blank/composer.json for theme

Language Package

/vendor/magento/language-en_us/composer.json for language