Waddesdon Station was indeed some distance from the village of that name hence it was called Waddesdon Road. If you follow the road from the A41 towards Quianton, you will notice that the south side of this road has an unusually wide verge, this being more trackbed for the tramway.
Don't know the difference between a 'tramway' and 'light railway' but I do know to be classed as a 'light railway' the trains must have a maximum (average) speed of 25 mph, hence many preserved lines nowadays use this bit of legislation to make their operation easier, and hence (for instance) the Watercress Line can still let pacifics have their head occasionally!!