E1 (Estrone) is the form of Estrogen that our Fat cells make. It is the PRIMARY estrogen of the body AFTER menopause. It is also most associated with breast cancer. This is why heavy set women are at much higher risk of breast cancer than thin women. Their ESTRONE levels are higher.

E2 is the form of Estrogen that our ovaries produce before menopause. It has NO increased risk of breast cancer. During the menopausal years and up to 10 years (or more) following menopause, Estradiol DECREASES our risk of breast cancer. Unfortunately, Estradiol (E2) can convert to Estrone (E1) - the estrogen we don't want. THIS is the reason, I don't recommend using Estradiol by ITSELF for too many without mixing it with our "Angel Estrogen" E3.

Now lets examine the Angel Estrogen, E3.
E3 is the form of Estrogen our body makes ONLY when we are pregnant. It DECREASES our risk of breast cancer. It does not have any conversion to Estradiol OR Estrone. It is an "END of the Line" - "END of the Chain" Estrogen. This is the reason Anti-Aging / Functional Medical physicians LOVE Estriol (E3).

Hormone Heaven, the Young Hormones product that I use, is 80% E3 and 20% E2 (as well as mixed with the perfect ratio of Progesterone.) It is a LOVELY and PROVEN combination of Safe and Effective Hormone Replacement! You can check out our line of Young Hormones on our website! 
https://drkarenleggett.com/pages/young-hormones

Hormone Protect is Progesterone Only for younger women

Hormone Heaven is BiEst with 80% E3 and 20% E2 with Progesterone. This is the one I use. It's perfect for a couple years before menopause to "whenever" AFTER menopause if you are thin OR up to 3-5 years after menopause if you need to lose weight.

Hormone Support is 100% E3 and Progesterone for years after menopause. I also recommend this one for women who need to lose weight and therefore I suspect their E1 levels are already higher than optimal. I hope this helps you understand the critical differences of the three Estrogen's!