Correct, what you want to watch out for is "scale"wheels". This is mostly MTH advertising lingo but does apply to other brands and the hobby in general.
Scale wheels have smaller scale flanges, and thus take larger diameter curves in track plans and also ideally run with scale style rails with proper railhead shape compared to tubular and other less scale like types of track.
Also, scale wheels typically are also made for 2 rail track setup and MTH made most of these engines 2 and 3 rail "capable" to bridge the market between those who wanted scale appearance, but not ready to give up 3 rails, but then later also capable of 2 rail function.
High rail= normal 3 rail O scale typical trains with normal taller non-scale flanges. Runs on most tracks (tubular, fastrack, scaletrax, realtrax, ross, gargraves, atlas, k-line).
Scale wheels= fine scale wheels meant typically for modelers wanting that extra bit of detail down to the track they run on and the wheel flanges. Because they are scale and smaller, then the track has to be that much more perfect, that much more in scale, larger diameter turns and so forth.