There is no difference between area  and topic.  areas  are the physical way of structuring and classifying information, while topics are logical views of the information. So you cannot differentiate between these two.

you can read more here
kjellsj.blogspot.com/.../...as-and-topics-for.html

Here is some code that may help you:

m_PortalContext = PortalApplication.GetContext(this.Context);

Guid guidHome = AreaManager.GetSystemAreaGuid(m_PortalContext, SystemArea.Home);

Area areaHome = AreaManager.GetArea(m_PortalContext, guidHome);

foreach(Area area  in areaHome.Areas) {

//Call recursive function here, passing in the area object, from which you can get area.Areas//

}

Please remember that we are all contributing on here as a volunteer effort. Some times  we get overwhelmed with our day-to-day activities and are not able to respond right away.

The code below is not getting me an area  and all its sub Area in one iteration (For Loop). For each layer I have to make a new for loop… that wuld put me in difficult. I am iterating based on keywords set on the area.

What you need to do is put the code inside of a recursive function.