HO vs N scale

My sons are the ones who brought me into the hobby. We slapped a table together and eventually ripped it out for the "do-over". The second one we thought through a little better (with inputs from forums). Dominic drove the specs. The result: we built a 8' x 10' L shape to my older son's specs.

I am thinking about a "grown up" table in N-scale, mostly because I would like to make some big hills and cliffs. What are the big differences in construction? Is it the same but smaller? What do you need to be careful with?

My boys' videos are below.

The introduction is episode I:
http://www.youtube.com/watch?v=dbDJDfI7wVE

Then the friend comes over and they shoot episode II: http://www.youtube.com/watch?v=zEssEmMIuwo