What's the difference between a Piece and a Scale Model?

A Scale Model is the canonical record of a manufacturer's product — e.g. "Lionel 6-18000 NYC J3a Hudson". One scale model is shared across the whole community.

A Piece is your physical copy of that scale model — the one sitting on your shelf or running on your layout. Two collectors who both own the same Hudson have two distinct Pieces but reference the same Scale Model record.

Why split them? It lets us share canonical data (specs, photos, MSRP) while still tracking the details that vary per copy (purchase price, condition, custom decals, your notes).