Technically this is the 'live steam locomotives' sub-topic under the 'model engineering' topic.
Perhaps full size railways should be in the 'Tea Room' with 'Aircraft General Discussion'?
Curiously, given how much it's talked about, we don't have a topic/sub-topic for full size engineering!
The correct terms are 'railway locomotives' and 'road locomotives' 
Traction engines are a very specific type of road locomotive, the steam equivalent of a tractor unit (which are those things you see pulling semi-trailers around our motorways.
Oh! Joy of Pedantry 
… or perhaps we can all fret a bit less about exactly which topic something is posted under, join the threads that interest us and pass over those that don't and leave them for the folks they do.
Neil