The cost of operating this bb is $2000+ a year.

Close to half of that comes from purchased banner ads and donations.
The rest has to come from google ads etc.
Fortunately the PR rating of the chipguide.com domain is high enough that it gets enough hits to generate the $$.

Aside from that, some of the software scripts that drive these bb's have to be installed within an html site. None of the bb's are html driven. The chipguide.com domain hosts those scripts and shares them, your profiles and preferences, and uploaded images, between the bb's.

That is the reason the set up is as it is.
The only reason the maps may be different today is that it looks like Charles temporarily disabled a couple of links while working on things. Ordinarily they are identical.

Remember that one domain is a commercial site while one is a not for profit.
That does place limitations on advertising and explains why the links on the left hand side are not identical on both. It is supposed to be like that.