WordPress Customizer vs. Full Site Editor
The Real Difference in Capability
The Customizer works within a fixed set of options a classic theme's developer decided to expose — if the theme didn't build a Customizer setting for something, it generally can't be changed through this interface at all, requiring custom CSS or code instead. The Site Editor, available only with block themes, works at a fundamentally different level, letting you directly edit the actual template files (the header, the post layout, the footer) visually, block by block, rather than being limited to whatever settings panel the theme predefined.
Which One Applies to a Given Site
- A classic (non-block) theme uses the Customizer exclusively, since it isn't built with the template structure the Site Editor requires.
- A modern block theme uses the Site Editor as its primary customization interface, generally offering the Customizer only in a reduced or absent form, since the Site Editor supersedes most of what it used to provide.
- Migrating from a classic theme to a block theme represents a real shift in how customization works, not just a visual refresh — existing Customizer-based customizations don't automatically translate to Site Editor equivalents.
- The Site Editor's greater power also means greater care is needed, since directly editing templates has more potential to visually break something than the more constrained Customizer interface.
Working With Either Tool
- Check whether the active theme is classic or block-based to know which tool actually applies.
- For a block theme, use the Site Editor for template-level customization rather than looking for an equivalent Customizer setting that may not exist.
- Test Site Editor changes carefully, given the greater scope of what can be directly modified.
Need help customizing your site's design with either tool? See WordPress bug fix.