At least in the First World (US, UK, Europe, Australia, Canada) generic pharmaceuticals are legally required to deliver the same drugs within a tolerance (usually no more than 10% in a worst case scenario... more often something like 1 per cent). This is enforced by random testing and license revocation. Generic drugs are designed to be a direct replacement of brand-names - they do not have "less" or "lower quality" ingredients, nor do they have inactive fillers that greatly modify drug activity... a large percentage of people complaining about their switch to generic medications is a simple nocebo effect. That, or they're buying pills off the street - pharmacies don't dispense "fake" generics that "look like the real thing" unless you're buying across the boder in Mexico... but I digress.
If you read the rules, we don't discuss generic pills vs Brand names here.