According to the FDA, there is supposed to be no difference whatsoever, except for packaging and possibly the exterior appearance of the pill/medication (i.e. the capsules of a generic brand are white and pink, where as the authentic brand is white and green) The generic is supposed to have the same quality and quantity of medicinal ingredient as the authentic. However, the generic brands are usually less expensive than the advertised brands. (Go to Wal-mart and look at brand name Tylenol and compare price with generic acetimenophen)
Pharmacists are required to fill prescriptions with generic drugs unless the doctor's prescription specifically requests brand name medicine (Aspirin Brand as opposed to generic acetylsalicylic acid pills). If you would prefer to have brand name pills, tell your doctor that when he/she is writing out your prescription.
Yup the only difference is the look of the medication and packaging. There are a few exceptions with items off the shelf but very few and if you read the boxes it should be very clear which ones will be different.
According to my new health insurance company, who I would like to kick in the behind, sometimes generics can have side effects that name brands don't, which I think is a bunch of crud, as they are forcing me to take a name brand prescription that I had been already taking the generic version of for a year, with NO side effects!!