A blog is short for "web log". The important structural distinction that makes something a blog, rather than some other kind of web page, is that it is divided into chronological units, and it displays in reverse chronological order. A blog is like an online diary.
A hub is a web article posted on Hubpages. If we had followed the linguistic development in blog, we might have called hubs "barticles". But that doesn't sound so good, does it?