In plain words
The short answer
Leaving the Bolt browser preview means the files start on a host you chose. Bolt Cloud publishing gives a free bolt.host address and can keep a backend. Netlify can host a site that runs in the browser, but it cannot host a database. GitHub keeps the files. A download is a zip. Done means the site opens on bolt.host, Netlify, or a host you started from GitHub or the zip — without opening Bolt.new.