When a CFG applies
For conventional foods, food additives, food-contact substances, and infant formula that meet applicable requirements, FDA offers a Certificate to a Foreign Government. For medical devices, the product must meet the relevant marketing conditions, establishment registration, device listing, and applicable authorization, clearance, or exemption with FDA. "Legally marketed" doesn't always mean "FDA approved." Depending on the product, legal marketing may result from clearance, approval, exemption, listing, or another applicable regulatory status, not necessarily from a premarket approval process.
When a COE is used
The Certificate of Exportability is used for certain products that don't follow the same domestic marketing path as a CFG, but that may be legally exported under specific provisions. For food, the COE covers certain products that may not be legally marketed within the United States but that may be exported under section 801(e)(1). For medical devices, FDA has different classes of COE depending on the applicable legal basis: one route under section 801(e)(1) and another under section 802. It does not automatically make every noncompliant product exportable, and the pathway to obtain one varies by product type and by the reason the product cannot be sold domestically.
Veterinary products
FDA's Center for Veterinary Medicine (CVM) also issues a Certificate of Free Sale, but for a different category: animal food, medicated feed, and animal drugs that meet applicable U.S. marketing requirements. Product category matters because different FDA centers administer their own, independent export-certificate programs.