I saw an article which proposed to show the obvious difference between a brand name and a generic. An element of proof was a cross-sectional picture of each kind of tablet, showing that the generic had coarse little granules of (presumed) medication in them, the brand name looked homogeneous.
The problem is that, the two important questions are 1) did this affect the absorption of the medication, and 2) did that make a difference as to the effective action of the drug?
For many drugs where the half-life is 12+ hrs, it probably won't matter, though getting to a steady-state level may be more erratic with the generic.