What are the main concepts that Diamond brings up in Guns, Germs and Steel which Mann diverges from them in 1493?

The central thesis
that Diamond argues in his convincing work is that the way that world history has played out is
not as a result of any difference between ethnicities and races, as was assumed for so long.
White Eurasians for example thought that the reason they dominated the world for long periods
was thanks to their God-given status as superior beings over other ethnicities. Diamond
successfully debunks this myth by arguing that difference between different groups of people was
actually unimportant, and in fact had nothing to do with which group came out on top of the
struggle for dominance in world history. Taking far-reaching examples to support his case,
Diamond argues...