You are comparing a integrated GPU(RXVega 7) with a dedicated GPU(RX590). Of course the 590 is better, and it is not Ryzen, unless you mean something else.
RX 590 is substantially better than the APU-iGPU from the 5600g. RX 560/570 is too, as well as the RX 550. 5600g is about on par with something like an older GTX 750 (non TI).