This is not actually true. Tren is tren when we're talking about tren ace, tren hex and tren enanthate. Methyl tren is an entirely different animal. Carbon 17alpha methylation changes a steroid completely. There are a lot of examples of this out there, for example the difference between Superdrol and Masteron are amazing, and even the difference between Superdrol and Dimethazine, which is more or less two Superdrol atoms attached with an azine bond.
Chemistry is an interesting subject