How am I supposed to be using these buttons?

I use a Nuova Simonelli Auriela Wave 2 group variable machine at my work. The guy who trained me said there’s no difference between the buttons on the left and the right but there obviously is! I don’t know what drinks to use the different buttons for – I’ve been using the left ones (shorter pull) for every drink but guessing this isn’t how it’s supposed to be used?! Can anyone advise?