Themes
A theme is a typography + color + spacing system applied at the site level. Edit a theme variable (primary color, heading font), and every page using that theme updates.
Templates
A template is a page skeleton — hero + body grid + footer. New pages can start from a template instead of a blank canvas. Changes to the template don't override existing pages; they only seed new ones.
Component library
Saved blocks (your branded hero, your branded footer) live in the component library. Insert by reference, not copy. Edit once, propagate everywhere.
Versioning
Themes and templates are versioned. Pin a critical campaign page to a specific theme version if you don't want it to shift when you redesign the global theme.