In simplest words so you don't have to read any further here's the breakdown nice and simple
"Forums = Discussion"
Articles = Objective/Factual
Aside from that lets look at some of the characteristics of each.
A forum is an exchange of ideas where people can discuss a variety of concepts generally related to the websites underlying theme. In our case it is Real Estate Investing.
So how is a forum different from blogging?..
Where is the best place to place free articles?...
How do I get specific location traffic coming to my site, if I want motivate sellers from a particular area?..is that possible?..