A drum is structural, a board is a surface
A cake drum is the half-inch thick laminated round that carries the weight. A thin cake board is a presentation surface that sits between layers or under a single light tier. People use the words interchangeably and then wonder why a two tier bake flexes on the way to the table.
If the cake leaves the kitchen — a car, a venue, a cold room — put it on a drum. If it is a single sponge going five feet to a dining table, a board is fine.
Go two inches wider than the cake
An 8 inch cake wants a 10 inch drum, a 10 inch cake wants a 12, and a 12 inch cake wants a 14. The margin is not decoration: it is where fingers go, it is what a board-lifter grips, and it is the buffer that stops a buttercream edge taking a knock at the door.
For a tiered bake, the base drum follows the base tier and every tier above it sits on a board cut to its own diameter. That is the whole system.
Colour is a background, so pick it against the cake
White reads clean under pastel and under naked sponge. Black makes bright buttercream and metallic work pop, and it hides crumb better than anything else. Gold is the celebration board — it photographs warm and it carries a plain cake further than any piping will.
All three of ours are grease resistant on the face. The reason that matters is simple: oil wicking out of a sponge into bare cardboard shows as a dark halo within an hour, and no amount of ribbon hides it.
Look after a drum and it survives the week
Keep drums flat and dry before use — a bowed drum will not sit flat again. After a bake, wipe the face rather than washing it; these are laminated boards, not plastic plates, and a soak will lift the edge.
If you are transporting, a non-slip mat under the drum does more for a cake than any amount of dowelling. Most tier failures we hear about are sliding, not collapsing.