ati are being cheeky.

what is a 58xx on desktop is a 1600 shader part (2.10B transistors)
what is a 58xx on mobile is a 800 shader part (1.07B transistors)

what is a 57/6xx on desktop is a 800 shader part (1.07B transistors)
what is a 57/6xx on mobile is a 400 shader part (0.67B transistors)

what is a 54/5xx on desktop is a 400 shader part (0.67B transistors)
what is a 54/5xx on mobile is a 80 shader part (0.24B transistors)

still a £500 laptop with a 400 shader GPU with a 128bit DDR5 bus is good value.