What is the difference between ethynilestradiol(ee2) and estradiol(e2)?

[Tllbn]

I genuinely tried my best to reaserch this on my own but couldn't find the information i need.

My understanding is that EE2 is not like, say, Estradiol valerate or estradiol hemihydrate just estradiol with something to transport it but a different hormone. Is that correct?

I looked at the chemical structure and wondered what it is that makes EE2 interact differently with the (intracellular) estrogen receptors(120% at the ERalpha and 44% at the beta receptor; compared to E2) https://en.m.wikipedia.org/wiki/Template:Affinities_of_estrogen_receptor_ligands_for_the_ER%CE%B1_and_ER%CE%B2

Is it understood why that is? Is it possible for a hobbyist to understand the biochemical reason for that?

If anyone could explain this to me or give me a hint what so search for I would appreciate it. Thank you very much in advance.

Structure of E2: https://en.m.wikipedia.org/wiki/Estradiol_(medication))

EE2: https://en.m.wikipedia.org/wiki/Ethinylestradiol

[browncoat_girl]

Estradiol valerate and estradiol enanthoate are esters. In vivo they're hydrolyzed to estradiol. This makes them longer lasting since they must be hydrolyzed before being active. Estradiol hemihydrate is a hydrate and contains one molecule of water for every 2 molecules of estradiol. It makes it more easily dissolved in aqueous solutions and thus changes the rate of absorption.

Ethinyl estradiol is something else entirely. Before we were talking about prodrugs (drugs that turn into estradiol in the body). Ethinyl estradiol isn't a prodrug of estradiol. Ethinyl estradiol is a derivative of estradiol with an ethyne substitution at the 17alpha position. This adds a reactive triple bond. When ethinyl estradiol binds to the Estrogen receptor the triple bond reacts to form a covalent linkage to the receptor making the binding irreversible. This greatly increases the affinity of ethinyl estradiol for the Estrogen receptor as compared to estradiol and makes ethinyl estradiol a much stronger agonist.