I can add just a little here. Bioidentical hormones are plant (soy) based and are "suppose" to match our chemistry better than synthetic. Synthetic estrogen is derived from the urine of pregnant horses, and doesn't match our biological make up. Suzanne Sommers is a strong supporter of bioidentical hormones, according to her, they helped her fight breast cancer.
(They believe synthetic HRT is what caused my mother's breast cancer)