When you create a model file in studio, you are creating a ModelType. An example would be "Shipment".
A single model can have multiple "levels", which are ModelLevelTypes. For example, in the Shipment model, we have the Shipment "header" as one level (contains the ship from location, ship to location, etc) and another level for Shipment Line (where you can have multiple deliveries, e.g. computer, monitor, keyboard, mouse as different lines).
So in this case, you have Shipment as a model type, and you have the Shipment header as a model level and the Shipment Line as a model level.
Each model level always corresponds to one table. A model contains 1 or more model levels, and thus implicitly means multiple tables.