You also need to be careful of the route.

The cheaper ticket is only valid on trains travelling via Baden and Frick as the SBB charge by distance.

The non-stop trains travel via Olten and Liestal which is a couple of francs more expensive. This is no biggie on an IC/IR, the conductor will sell you an excess (with a 5CHF penalty) but on a local train a mistake could cost you 80 CHF, do it enough times and you'll be discussing it with a judge.

The Frick route is 30 CHF, the Olten route is 31 CHF so no drastic consequences. if you're using the machines (quite easy) then select the Olten route and then you're covered.