The 2 methods apply the same ISO 14064-1 standard and cover the same gases and the same scopes, and their results convert from one to the other without fresh data collection. They differ in 5 areas: how emission categories are organised (11 for Bilan Carbone® V9, 15 Scope 3 categories for the GHG Protocol), emission factor databases (ADEME's Base Empreinte on one side, multiple sources on the other), the treatment of Scope 2, practitioner certification (by ABC for Bilan Carbone®, with no equivalent for the GHG Protocol) and the ecosystem (ADEME and the BEGES in France; CDP, SBTi and ISSB internationally).
Read the source article: Bilan Carbone® vs GHG Protocol: the 5 differences that matter