An APU - a CPU with an integrated GPU inside of it. An APU is a very interesting idea because not only is it a cheap alternative if you can't afford a GPU, with an apu alone you can play games on medium/low settings, including modern games. Consider it as a brain and eyes. You can also crossfire the integrated graphics with another GPU installed onto the motherboard. An APU is a very beautiful creation, though in my opinion needs work to come to its "full potential". APUs cannot yet surpass a separate mid-high end CPU & GPU in rendering.
FX - The FX series are just CPUs. These are purely the brain of your motherboard and focus on nothing else but being the brain. The FX CPU can only "think" and not "see" like an APU can.
So compare the a10 and the 8350 alone in computing bench. The 8350 will always win in rendering/encoding/transcoding/etc.
But for a suitable comparison,
I would compare the A10 to be on par with the FX4300(no GPU), only it has an integrated GPU.