My experience for the most part is that outdoor can be just as strong/potent as indoor but its almost always more harsh. Just the dust and random particles in the air that collect on it from being outside will give the bud a darker color and make it smoke harsher than equivalent indoor.

Not really a big deal either way but like if I'm taking fat bong rips or smoking an entire joint to my dome my throat can feel damn scratchy afterward if it was outdoor.