An ISBN identifies an edition of a book; copyright protects original expression. They are related to publishing but they are not the same thing. Authors should know who owns the rights, files and accounts before approving publication.
What an ISBN does
An ISBN identifies a specific format and edition for booksellers, libraries and distribution systems. Paperback, hardcover and some other editions may require separate identifiers.
What copyright covers
Copyright generally concerns ownership of original creative work. Registration procedures and legal effects vary by country, so authors needing legal advice should consult a qualified professional.
Questions to ask a service provider
Ask whose name appears as publisher, who controls the retailer account, who receives royalties, which rights are licensed, and whether editable and print-ready files will be delivered.
This guide provides general publishing information, not legal, tax or guaranteed commercial advice. Platform rules and fees can change; verify current requirements with the relevant platform.