The scope of digital curation at the BnF covers documents digitized from BnF collections as well as born-digital material bought by the BnF or collected under its legal deposit mandate. It is therefore critical for the library to investigate if common approaches may be adopted for similar document types, whatever their origin may be. This paper proposes to focus on the case of electronic books (or ebooks), by comparing the way BnF teams intend to ensure the long term preservation of those directly digitized by the library and those that will enter through legal deposit.Data and metadata formats are different, even though EPUB appears as the reference format for both kinds of ebooks. Acquisition procedures are necessarily specific. However, for the other steps of the treatment process, digitized and born digital books should follow similar and parallel workflows: indexing in BnF General Catalogue, access through the digital library Gallica and preservation in SPAR, BnF's digital repository. Common validation tools, characterization schemes and preservation metadata will be used in order to preserve both faces of French digital heritage.