FIFA 21 uses virtual currencies for rewards and buying packs & items in FIFA Ultimate Team mode.
FIFA coins can be gained by playing matches, completing objectives and sometimes can be found in the packs. FIFA points can be used to open FIFA 21 packs only. FIFA points can be bought by real money only. 100 FIFA Points cost about USD 1.
For running and improving your club in FIFA Ultimate Team (FUT) you will need to spend FIFA coins, but having and spending FIFA Points is not necessary. The idea for FIFA Points is to open packs without spending coins, which means to earn coins you need to play matches, while FIFA Points can be directly bought from FUT store and you won't need to spend time by playing FUT games.
Buying and selling FIFA Points and coins are banned by EA, which means if EA realised that your club's coins or points our bought from a third party seller or you are selling your coins/points to other people, they will ban and suspend your FIFA account.