I was involved in HO when I was "younger" ... MANY years ago - I am now 61 and getting ready to retire. My wife has bought me 3 series of the Hawthorne Valley Bachmann trains (USA Navy, NE Patriots, and McDonald's. They are advertised as "HO" but after some quick research it appears that they are truly Bachmann On30 trains. This is Brand New to me. What is the difference between Bachmann On30 trains and HO. I have a space of 10' X 20' that I plan to set up a layout on and build up over the next several years. I want to make sure I do this right. Any guidance one can provide to set me in the right direction would be appreciated ... looking forward to get back into the Model RR game ..... Thanks