- a driving dimension will change the geometry of the model (like when you ask your foreman in real life to "make this bar 3" long").
- a driven dimension will only measure an existing model without affecting it ("please check this bar and tell me how long it is").
- a driving dimension drives the model (change the dimension => change the model)
- a driven or reference dimension is driven by the model (change the model => change the dimension)
It now seems so self explanatory. Thanks!