You do not buy tickets for trains. You buy a ticket eg. from Basel to Zurich, and you can use it on any train that goes from Basel to Zurich on the day it is valid. So you can use it on IR, IC, ICE and even TGV services.
That is how people travel here. You buy a ticket, and then take the best train for the trip you plan to take. And most people just buy their ticket shortly before travel. This is all mass transit basically.
But you can sometimes buy supersaver tickets, when you buy in advance, and these are indeed limited to the train you selected during purchase.