Page Builders are specialized plugin families. They include a page editor which usually consists of several building blocks which allow for extreme customization, building block code modules and the page display unit at a minimum.
The top free are:
The top paid builders are:
WPBakery Page Builder (formerly Visual Composer)
References:
http://www.wpbeginner.com/beginners-guide/best-drag-and-drop-page-builders-for-wordpress/
https://athemes.com/collections/drag-drop-page-builders-wordpress/