Let me pose a question. Why is it that a .5mg xanax pill is actually more like 300mg of stuff? Well besides the fact that it needs to be swallowable, it has to do with the placebo effect.
Humans actually get a slight placebo effect boost from drugs like anxiety meds, because of the size of the pill. This goes for opiate based painkillers and NSAIDs even. .5mg of alprazolam literally looks like less than one grain of sand.
How do you think it would affect your anxiety if instead of "popping a pill" you dabbed a grain of sand onto your tongue? I bet you wouldnt be AS sedated as popping the pill, because of the placebo effect.
Thats all thats going on. Placebo effect with the "green pill". Most likely because your brains wiring has "positive associations" with taking the green pill over other pills, and therefore your subconscious is tricking your conscious into thinking the green one is more effective...because it IS! but not because of the manufacturer, because of PLACEBO.
its like a self-fulfilling prophecy....except the manufacturer has nothing to do with it, alprazolam is alprazolam, your subconscious positive associations with that manufacturer, however, may cause a slight increase in effectiveness. Make sense? It has to do with the reward system in the brain.
unless of course theres isomers of alprazolam that are less effective??? (...searching wiki...)