Exactly, methyltren is a different steroid than "regular" trenbolone. Mike Arnold described this difference very nicely in his posts.
How often do you take Tren Ace and Tren Enan? I think one of the factors contributing to Tren side effects (aside from histamine, which bbextreme described VERY well in his article) is concentration fluctuations.
If I take Tren Ace ED and Tren Enan E2D (of course not at the same time), I don't feel any concentration fluctuations and it's fine. And I don't notice much difference between the two esters either. If someone is taking Tren Ace E2D and Tren Enan E4D, they should try more frequent, smaller doses and see how the side effects go.