I can't speak for your childhood, Joe :)
I was clarifying the OP's reference to "Puffin' Billy marketing" in Australia.
But yes, the terms Puffing Billy / Pufferbilly are, I reckon, probably synonymous with steam locomotives.....

I do miss Steam Trains. Mucky and gritty the journey may have been, but as a kid I just loved the smell of the smoke, LoL!

R-J