The primary difference lies in the active chemical agent and the classes of fire they suppress:
• ABC Powder: Uses Monoammonium Phosphate (typically 50% to 90% concentration). It is highly versatile and suppresses Class A (trash, wood, paper), Class B (liquids), and Class C (electrical/gas) fires.
• BC Powder: Uses Sodium Bicarbonate or Potassium Bicarbonate. It is only suitable for Class B (liquids) and Class C (electrical) fires, and is highly ineffective against deep-seated wood/paper Class A fires.