what is the brand / model?
A boiler machine will have a... um... boiler - its hard to miss - usually a copper cylindrical tank.
are those photos of the top of the group head?
[edit: another way to tell]
Does it have a hot water wand? Get it really hot, turn it off, and then open the hot water wand (or steam wand) and see what comes out. If its a boiler, lots of water (or steam) will come out when switched off and hot thanks to the boiler pressure.