1| You do realize that there are various SKu's for the processor you've mentioned right? There are model numbers to denote what you're buying.
2| What games have you tried on all three units to gauge that your laptop is crippled?
3| The APU can be argued to take help from the higher ram capacity (and possibly higher frequency'd ram). Again that will be revealed when you share the SKU of all the laptop's or at least the detailed specs of all three laptops.
4| Are you all on the same OS as well?
R5 is the name of the GPU series, there are many different models in that series with different levels of performance. Also saying i7 v i5 doesn't meant anything, again need to know exact model. It's entirely possible for a modern i5 to outperform an older i7 in games.
The "Radeon R5" is a family of GPUs. Not only are there integrated Radeon R5, but there are dedicated GPUs that are Radeon R5 each with different model numbers. If a laptop with an Intel CPU has a Radeon R5, then that is a dedicated GPU (only AMD APUs have integrated Radeon graphics core), but without any specific model (like the Radeon R5 M335), then it is impossible to say which dedicated GPU it has.