Some of both. I think it's mostly the model. * All of a single product is from the same vendor. Very often, that vendor is also the manufacturer. (model) *

Some of both. I think it's mostly the model. * All of a single product is from the same vendor. Very often, that vendor is also the manufacturer. (model) * Grocery stores have limited shelf space, and thus spend time getting to know their products. (model influencing qa)