An HSA, or Health Savings Account, is a type of savings account that enables you to set aside funds, PRE-TAX, to pay for medical expenses that qualify. A few examples of qualified expenses are deductibles, copayments, and coinsurance, and others. One thing HSAs CAN NOT be used for is existing premiums for insurance policies.
FSA, or Flexible Spending Account, is a special account one can put money into to pay for out-of-pocket health expenses such as deductibles, copayments, and over-the-counter medications. FSA funds may NOT be used to cover existing insurance premiums.