Think of it this way.

A CPU is a big digger, its bucket can dig a large chunk of earth with one scoop. Heavy lifting.

A GPU is a lot of small shovels, each digging a small amount of earth, but all at the same time.

So a CPU can do a large task at once, a GPU can do a lot of smaller tasks at once.

Which is great, the CPU is doing grunt work, the GPU is doing small calculations.

Both the GPU and the CPU being perfectly tasked for their specific purpose.