AFFF Fire Extinguishers and Foam Fire Extinguishers are two names for the same thing – but be careful, because AFFF extinguishers contain a proportion of water, so they are not recommended for fires where live electricity is involved.
A foam fire extinguisher can be used to fight Class A fires involving wood, paper, textiles, coal or similar materials, as well as Class B flammable liquid fires. That makes them more versatile than water extinguishers, and a lighter and smaller alternative for an equivalent fire.