At the end of every (or most) Brooklyn Nine-Nine episodes there is a "Promotional Consideration Furnished by Apple" message shown during the credits.

Does that mean that Apple pays for the product placement in the series? Or do they supply the products used as props (mobile phones, laptops, etc)? Is there a difference in the way to disclaim that?

In general, “Promotional Consideration” could mean that fees have been paid to the production, but not necessarily. It could mean that they provided product without rental fees, provided some support without charging the production - for example installing a working phone system in an office set - or provide product that does not need to be returned. Basically it means that some monetary value was provided.

Since Apple never pays fees for placement, in these cases it means they have provided products either for use in the program.

It is also seen on game shows. For example, if you were on “Let’s Make A Deal” and you won a brand new iPad Pro, the company that produces Let’s Make A Deal does not buy the iPad Pro. Instead, Apple provides the unit for free in exchange for the publicity it generates. The free iPad is furnished to promote Apple products, therefore the item is considered promotional.