Amazon itself, sells many things. Everything listed on Amazon is not offered by Amazon tho. Much of Amazon's wide breadth of inventory is supplied by independent retailers. So, Amazon is both a retailer, and an operator of a marketplace (of 3rd party sellers).

Amazon and Google both provide datacenter services.

The similarities don't extend much beyond either of these points.

Oh, and all three are headquartered in the Pacific mid-to-northwest.