From my perspective, the difference between Gutenberg and Page Builders is architectural intent. Gutenberg is a block manager / editor model. A Page Builder is an integrated design studio.

Differences:

- GB is a component, Page Builders are applications
- GB is a block manager / editor, Page Builders are integrated design studios
- GB focus is narrow so risk to the operational WordPress server is minimised, Page Builders are complex applications that add unnecessary risk to an operational server relative to an arms-length design studio
- GB has a reasonably bounded server footprint (RAM / Disk), Page Builders are unbounded and could grow to dwarf the size of the WordPress CMS.
-GB is a 2-way model (well...as far as I have seen), page-builders are 1-way model. You can manually edit a GB component and save it as a new GB component. Page builders are 1-way...use their visual interface for everything because any manual adjustments are unlikely to survive more than a few page builder updates...if any.

The WordPress landscape is littered with the corpses of WordPress design studios...arms-length (e.g. Artisteer) and integrated (e.g. Headway).

As long as Gutenberg remains a block manager / editor...it will have my full support. Go Gutenberg :-)