This page will explain all the features that are of influence on the cycling experience, such as cycling smoothness, inertia and all extra features that comes with the trainer.
The basic trainers have a flywheel equipped. The heavier the flywheel the better cycling feel inertia you have. They are between 1,2 kilo (twist) and 1,6 kilogram (other).
The trainers have a resistance lever of 10 positions. This way you can change the resistance.
If you connect a T2015 speed/cadence sensor then you have the possibility to use Virtual power in the App. Tacx will release the Tacx Training app in November 2018 were all the trainers can be selected.