What is the difference between anhydrous formic acid and formic acid?

Formic acid is widely used in chemical pharmacy, rubber coagulant, textile, printing and dyeing, electroplating, leather and other fields, and is the basic raw material of organic chemical industry. Usually, formic acid used in industry mainly refers to 85% formic acid. When the chemical concentration in eastern Sichuan is higher than 95%, it becomes concentrated formic acid, and the concentration above 99.5% is called anhydrous formic acid.