So, what would you say what these tools have learned and taken from autotools, and what are the core ideas with which they were improving? I was looking around

So, what would you say what these tools have learned and taken from autotools, and what are the core ideas with which they were improving? I was looking around for a description of what the core ideas of CMake are and could not find much, except automating for platforms which are not Unix-y or POSIX.