Hello, we will have a 3-day trip to Zurich. Are transportation cards valid on both train and bus?

Yes, I'm quite certain that transportation cards can be used on trains, buses and trams here in Zurich. You have to be sure that your card or ticket covers all of the "districts" that you'll be traveling within, though. (The Zurich area is divided into districts, and I think that when you buy a transportation card, it usually only covers travel within certain districts).

Hi,

normal transportation cards are valid on trains, trams and buses, but also on the lake ships and the cablecars. And yes, you don't have to worry about the type of vehicle you board, but you have to worry about these "districts" of validity (the official name is "zones").

This is a nice starting point to have an overview of transportation for a 3-day visit:
https://www.zvv.ch/zvv/en/travelcard...erichcard.html