Sure there are differences between pharma and UGL hGH (eg, excipients & fillers), but the question was why is pharma better.
The evidence suggests it's not -- testing purity dimer, serum GH assays, etc.
The back & forth will never stop though. Imagine if you stocked up on a ton of pharma GH pens then people post test reports showing they aren't better. You'd probably still say "I swear I can tell they're better" so you don't feel like you got ripped off.
I've bounced back & forth between UGL and pharma a few times and could never tell a difference, going up to 10 IU/d.