Either, in most cases. BRCGS Food Safety and IFS Food are both recognised against the same GFSI benchmark, so a buyer asking for one and receiving the other is usually asking a question about habit rather than about food safety. The choice follows the customer base, not the standard.
Why it works this way
Recognition is the point. GFSI benchmarking exists so that a site does not need four certificates to sell to four customers. Once two schemes clear the same benchmark, the difference between them is scoring mechanics, audit rhythm and the language the report is written in, not the level of food safety they require.
Where they diverge is commercial geography. BRCGS grew out of British retail and carries the letter grade that buyers there recognise on sight. IFS Food grew out of German and French retail and reports as a percentage with a Foundation or Higher level. A supplier selling mainly into UK retail and a supplier selling mainly into continental private label are answering different customers.
What follows in practice
Write the requirement as a GFSI-recognised scheme rather than as a named one, unless your own downstream customer names it in a contract. Naming one narrows your supply base for no food safety gain, and it pushes suppliers toward dual certification you will pay for in the price.
Then verify the certificate rather than the logo. Scope, sites, product categories, validity dates, the certification body and whether the audit was announced. BRCGS against IFS Food sets out where the two reports differ and how to read each one.