Masteron Enanthate, which should be more properly known as Drostanolone Enanthate or Mast E, is a long estered variant of Drostanolone. Drostanolone was originally marketed on the prescription drug market under the brand name Masteron, which was Drostanolone Propionate (a short estered variant of Drostalonone).
The trade name of Masteron caught on very quickly across bodybuilding circles, and the two should really be referred to as “Drostanolone Propionate” and “Drostanolone Enanthate” due to the fact that the brand name Masteron is really a descriptor for Drostanolone Propionate, and only Drostanolone Propionate.
However, the Masteron trade name has stuck permanently onto the lips of bodybuilders and athletes everywhere, and so the Enanthate variant of Drostanolone is now referred to all the time as Masteron Enanthate. Chemically, the difference between Masteron Propionate and Masteron Enanthate is very much the exact same as the difference between Testosterone Propionate and Testosterone Enanthate. The base hormone, which in this case is Drostanolone, is affixed with an Enanthate ester on its 17-beta hydroxyl group.