> I'd have thought that table & sheet the same.
Nope. Not in Numbers. That's an Excel thing, where a 'document' contains multiple 'sheets', where each sheet is a (potentially massive) grid of rows and columns.
In Numbers, a 'document' is a collection of 'sheets', and each sheet can contain any number of distinct 'tables', where each table is a grid of rows and columns.
So in Numbers, it's entirely possible (and common) to have a single 'sheet' that contains multiple 'tables'.
Any cell can reference any other cell in the same table (e.g. '=B4'), in another table on the same sheet (e.g. 'Table Name::B4'), or in another table on a different sheet (e.g. 'Sheet Name::Table Name::B4'), but Numbers won't let you reference cells in a completely different document.
If you want, you can have one table per sheet and mimic the Excel way, but it all depends on how you want to slice and dice your data.