Strange way of looking at it.
O Scale and O Gauge are often thought of as synonymous. Lionel has its own terms, none of which match scale and gauge.
While Paul's analysis may be strictly true - just as we do not use 1:48 Diesel engines to power our traction motors - models are compromises.
Most of us differentiate "scale" as having to do with overall dimensions and details, not flange clearance or whether our brakes actuate with air pressure.
If you really want to keep your wits about you when discussing scale and gauge, use the common nomenclature for gauge (Z, TT, N, HO, OO, S, Q, O, G) and use inch per foot (or mm per foot) for the scale. And please - all Q-gauge models were 1/4" to the foot, or 1:48. All of them.
Then, use Lionel's current nomenclature when discussing undersize Lionel, and MTH nomenclature when discussing MTH. As far as I can tell, nobody else is making undersize models for oversize track. This is a special area.
