Understanding the difference between theme fonts and installed fonts is crucial for block theme development. Theme fonts are declared in theme.json and stored in your theme directory, making them portable and version-controlled.
Installed fonts (added through the Font Library interface) are downloaded to the uploads directory and stored as database entries, similar to uploaded images. They have post entries for font families and font faces with references to the actual font files.
While the Font Library is excellent for end users, developers should export installed fonts to theme files using tools like Create Block Theme. This ensures fonts become part of your theme rather than site-specific database content.
The hash-named files in uploads and database dependencies make installed fonts less ideal for development workflows, but the export process solves this cleanly.