In the song: "Chattanooga Choo Choo" does 'Track 29' mean platform in Downunder speak? - Trains Magazine

As to the difference between platform and track, the platform is what people stand on to wait for the train or board the train. I would think that 'platform' would apply to both elevated and ground level boarding areas.

As for the song: the reason they say "track 29" is in those days at big union stations with multiple tracks they'd annouce which track number the train is arriving or departing to or from. Of course one platform can serve two tracks, one track on each side. But I think the tracks were numbered at the platforms and I don't know and I doubt the platforms were numbered, at least not as often as the tracks were.

It's like airport terminals, the gates are all numbered. At big stations the tracks were numbered. At little depots at small towns between the big cities there may have been only 1 or 2 tracks and there for only 1 or 2 platforms. I've noticed when riding Amtrak across the states of Kansas and Missouri, for instance, the train, on these double track lines, almost always crosses over to the track nearest the depot. I can't really remember a depot in these two states that didn't have more than 1 platform for stopping at except at Kansas City's Union Station which has two tracks. Usually the superliners (Chicago to LA )stop on the outter track and the smaller commuter train (KC to St Louis) stops on the track closer to the building (sometimes). I think maybe Kirkwood has boarding platforms for the two tracks but the train almost always stops on the track nearest the depot.

I'm not too familier if union stations today still have mulitple track numbers. Maybe LA, DC, NY, Philly, places with high volume of train traffic. Places like KC and St.L have all had their tracks ripped up years and years ago because of lack of passenger traffic.