there seems to be slightly different logic in what /usr/loca really means. ultimately /usr/bin etc.. is for base system programs, part of the core OS. /usr/local is for customized applications that you'd install yourself, from source etc... the difference comes in that /usr/local would be local to the individual machine when used in a netowrked enviornment. you have 1000 boxes running the same OS, they can therefore share a single /usr directory over NFS for example and run great guns. you then have a space on each machine i.e. /usr/local for local software only. so if you consider local software to be user installed software, then they are kinda identical.
Now on a standalone LFS box, the logic is just gonna fall flat on it's face really.. no networked FS, no distinction between OS and user apps... but it has it's uses.