This is from the "Linux From Scratch" project... where someone took the time to implement a more BSD style approach to booting.
As for a good explaination of the differences... the best I have ever seen was in The Unix System Administrator's Handbook.
it was a charm which walked you through full example scripts for each system and explained the differences and the design choices of each. Sadly, I do not know of any online source that does this. If I find one, I will be sure to post it here.
The the meantime, the LFS paper is a good read for understanding the way they are different and why some people would pick one over the other.