As for NEO & non-NEO, the NEO engined cars were the series 2, which you can tell from the front because they have the headlights with 2 seperate lenses, rather than all in one rectangular block.
Someone with more knowledge than me might be able to tell you in more detail, but that's an obvious difference.
Try http://www.geocities.com/mcnamg/ for more details of models, features, etc.