Complexity and sheer intelligence and capability required to build either.
And what is the basis for your claim? You are not impressed by AWS's complexity and intelligence and capability to build and manage 1-2 zettabytes of storage near flawlessly?
Im more impressed by red dead redemption 2 or baldurs gate 3.
There is no “basis” other my gut feeling. Unless you can get quantified metrics to compare that’s all we got. For example if you had lines of code for both, or average IQ. Both would lead towards the “basis” which neither you or I have.