 Yes, all of these actually do taste different and they are not all created equal. Cans have a polymer lining that can absorb the flavor making the drink taste more mild. The soda's flavor may be altered by some of the acetaldehyde and plastic bottles and carbonation can even leak out. Glass bottles typically won't change the taste, they keep carbonation and they can be stored longer. McDonald's has an unfair advantage because of its long history with the soda company. The syrups are delivered in stainless steel tanks opposed to plastic bags which get sent to other vendors. Syrups in filtered water get pre-chilled and the ratio of that syrup is even set to allow for the ice to melt.