What is the difference between esterified and conjugated estrogen?

Chemical structures: Esterified Estrogens are chemically different and most often are plant derived. The Conjugated Estrogens are a group of Estrogens that come from horses. There are several different forms of estrogen in the conjugated group. All Estrogens bind to the estrogen receptor and produce an estrogenic effect. Each estrogen though has different potency characteristics in it's receptor effect.