What Vellum does brilliantly, honestly stated
Vellum earned its reputation: import a manuscript, choose one of its book styles, and export retailer-ready ebook and print files from a native Mac application with famous polish. The license is one-time, covers unlimited books, and includes updates, which is genuinely economical for an author shipping several books a year on a Mac.
None of that requires correction. The comparison exists because two real situations sit outside it: authors who do not use a Mac, and authors with one book who hesitate at a $199.99 to $249.99 license before their first export.
Where Coverfairy takes a different route
Coverfairy runs in the browser on any machine, so there is nothing to install and no operating-system requirement. Formatting is free to try: drop in the Word file or EPUB, page through the typeset book, switch among eleven genre themes, and download a watermarked sample. The clean files, a validated EPUB, the KDP print PDF, and a large-print edition, are $19 once for that book.
The structural difference is that Coverfairy holds the whole book: the interior's real page count feeds the cover's spine calculation in the same project, the palette can flow between cover and interior, and the finished cover ships inside the Complete Book EPUB. Vellum deliberately formats interiors and leaves the cover to other tools.
Choosing between them
Choose Vellum if you work on a Mac, love native software, and expect to format many books; its unlimited license amortizes quickly. Choose Coverfairy if you are on Windows or a Chromebook, want to try the entire flow before paying, are producing one or a few books, or want the cover, spine, and interior synchronized in one place.
Both tools are one-time purchases rather than subscriptions, which the indie-author market has clearly voted for. Check current prices on both sites before deciding; the figures here were read from the vendors' public pages on the review date.