Most pharmacies and insurance plans default to generic prescription drugs. Your health insurance can get you prescription medication / drugs. But, If the treatment you need isn't life threatening then you should use generic drugs first.
Differences between Generic Drugs
There are very few differences between name-brand and generic drugs. But, there are big differences between generic drugs. Generic drugs are often manufactured by more than one company. Each pharmaceutical company may use its own recipe to manufacture a drug. That means that each company may have a different product to offer with varying degrees of effectiveness.
Chemically speaking, the differences can be overwhelming. Stereochemical differences in a drug, or mirror images of the same compound, may have a significant impact on its function in the body. Many stereoisomers of prescription drugs have no effect on the body because the chemical shape does not match the target organ or cells (look up L-Dopa and chirality for more info on stereochemistry).
Another example is how the drug is filled. Different fillers may affect the potency of a drug, or reduce its bioavailability altogether. While the later is less common, new drugs have new properties. Drugs that have been on the market for sometime are always better understood--and thus safer, but never foolproof.
How do I choose what drug to use?
Look up information on the company for the generic brand drug and what people have said. The internet is a good place to find reviews on different prescription and generic drugs. Also, you should discuss different options with your pharmacist. If your health insurance covers different pharmacies then this may be a significant advantage. Different stores carry different products. So, this will give a wider selection of generic brand drugs to choose from.