Hi robotwars
"Same same but different"... The active ingredient - estradiol - is the same but Sandrena is more concentrated than Oestrogel so you need less gel for the same amount of oestrogen - maybe better for those who need to use a lot? , In addition they contain slightly different ingredients :
Sandrena: ingredients in additional to estradiol (1 mg per g)
Carbomer 974P
Trolamine
Propylene glycol
Ethanol 96 %
Water, purified
Apparently propylene glycol can cause skin irritation in some.
Estrogel ingredients in addition to estradiol (0.6 mg per g)
Ethanol
-Carbomer
-Triethanolamine
-Purified water
Hurdity x