4-diol and 1-AD are prohormone supplements. They are chemical precursors to active sex hormones in the human body.
4-diol (4AD, Androdiol, 4-androstenediol) is a chemical precursor to testosterone in the human body.
1-AD (1-androstenediol, 5alpha-androst-1-en-3beta,17beta-diol) is a chemical precursor to a trace hormone found in the human body which is casually referred to as "1-testosterone." "1-testosterone" is thought to be more anabolically potent milligram for milligram than testosterone. It is also more androgenic.
Both prohormones are used to build muscle. Both prohormones have their own set of side effects - especially for women. Women wishing to augment lean muscle mass by using prohormone supplements would probably be better off starting out with NorDiol (19-nor-4-androstenediol). NorDiol is a prohormone which converts in the human body to nortestosterone (aka nandrolone) which is almost as anabolically potent as testosterone yet only about 25% as androgenic. This lower androgenicity should translate to a lower incidence of male-virilizing side-effects in the female prohormone user.
It is generally recommended that any prohormone user, especially a female, educate themselves as well as possible about the effects, side effects, and risks associated with prohormone supplementation before starting on a prohormone supplement regimen.