Shampoos and Conditioners have been around for many years and over these years, research in the personal care world has dictated what performs the best. Shampoos and Conditioners do not carry a similar chemistry and therefore are not alike.
Shampoos are for cleansing.
Conditioners are for conditioning. Conditioners are in a class of cationic surfactants. These type of products have a basic positively charged compound. This, along with the key component of a functional group gives the product its characteristic, such as a rich manageable satin look and feel to the hair. This basic chemistry in combination to the chemistry and physiology of the hair produces the desired end result.