While I don't think it's something to get Overly Concerned about.
This is the Difference between the 2 Tren Esters.
Tren Acetate ~ 83 Mg of Active Hormone per 100 Mg.
Tren Enanthate ~ 68 Mg of Active Hormone per 100 Mg.
You also need to look at the Half-Life of the Ester in question.
As the Enanthate will build-up over time due to it's Longer Half-Life.
Acetate ~ 3 Days
Enanthate ~ I've seen it at between 8 to 10.5 Days ~ I tend to go with the 8 Days.
This is what's known as Pharmacokinetics ~ a sub-Branch of Pharmacology.
Which is the Study of the Processes of Absorption/Distribution/Metabolism/and Elimination of a Drug.
This is why Half-Lives of a Steroid are often More Important than how much Active Hormone is available.......................... JP